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Zero Plastic Stains. Zero Commuter Bag Leaks.

Cosari VaultBox 304

Ditch warped, orange-stained plastic tubs forever.

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  • 360° Leak-Proof Crimson Seal: 4 scalloped side latches
  • Pure 304 (18/8) Stainless Steel: Non-porous brushed metal
  • See-Through Stack & Nest Design: Flat crystal-clear lid
  • 100% Usable Interior Volume: Smooth rounded corners and
Cosari VaultBox 304
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Engineered to Outlast a Decade of Daily Lunches

Every detail of the Cosari VaultBox 304 was built to eliminate the leaks, stains, and wasted space of ordinary plastic bento boxes.

4-Point Scalloped Latch Lock

Four translucent scalloped-edge side latches distribute clamping force evenly across all four sides so lids never pop open inside your bag.

Surgical-Grade 304 Stainless

Pressed from rust-proof 18/8 austenitic stainless steel that shrugs off acidic tomato sauces, chili oil, and daily high-heat dishwashing.

4 Graduated Stackable Sizes

From the 220ml snack pod and 600ml lunch box to the 1500ml meal-prep tub and 2900ml family container, every flat lid stacks flush.

Removable Hygiene Gasket

The deep-channel dark red silicone ring lifts out in seconds for thorough washing, ensuring zero hidden moisture or mold buildup.

How the VaultBox 304 Seals, Stacks & Cleans in Seconds

1. 360° Crimson Silicone Compression

1. 360° Crimson Silicone Compression

Press gently on the center of the crystal-clear lid and snap down the four scalloped-edge translucent latches. The thick dark red silicone ring compresses tightly against the rolled 304 steel rim to lock in dressings and liquids.

2. Modular Fridge & Bag Stacking

2. Modular Fridge & Bag Stacking

The recessed flat transparent lid creates a stable landing pad so smaller 220ml and 600ml boxes stack neatly atop the 1500ml or 2900ml tubs—saving half your refrigerator shelf space while keeping every meal visible.

3. One-Swipe Rounded Steel Cleanup

3. One-Swipe Rounded Steel Cleanup

With zero welded seams, sharp corners, or porous plastic pits, even overnight curry and pasta sauce rinse right off the brushed 304 stainless steel interior under warm water or in the dishwasher.

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Cosari VaultBox 304

Food-Grade 304 Brushed Stainless Steel Bento System with 360° Crimson Silicone Lock & Crystal-Clear Stackable Lid

Backed by our 30-Day Money-Back Trial & Full Cosari Guarantee.

$34.99 $69.99 Free Tracked Shipping (5–7 Days) Included

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30-Day Money-Back Guarantee plus a full 2-Year Warranty.

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Description

Why We Built It: Most lunch boxes force a bad trade-off: plastic containers have clear leak-proof lids but stain and warp within weeks, while traditional stainless steel boxes have opaque lids that leak salad dressing everywhere. The Cosari VaultBox 304 combines a hygienic 304 stainless steel tub with a see-through, four-latch silicone-sealed lid.

Capacity & Sizing Guide: Designed in four graduated capacities to cover every appetite: 220ml (snacks, berries, sauces), 600ml (kids' lunches, side salads, sandwiches), 1500ml (full adult commuter lunches & high-protein meal prep), and 2900ml (family batch prep & fridge organization). Empty steel bases nest inside one another to save cabinet space.

Materials & Care: Base: 100% 304 (18/8) food-grade brushed stainless steel. Lid: BPA-free shatter-resistant transparent polymer with 4 scalloped snap-lock latches and a removable food-grade crimson silicone gasket. Dishwasher and freezer safe (-20°C to +120°C). Always remove the clear lid before heating the steel base in an oven.

5–7 Day Shipping & 30-Day Returns

Free 5–7 Day US Shipping: Every order ships free with full tracking and delivers in 5 to 7 business days.

30-Day Trial: Try it at home for 30 days risk-free. Need help? Email us anytime at support@buycosari.com.

2-Year Warranty: If anything goes wrong within 2 years, we replace it free of charge or refund your order in full.

Why Choose the Cosari VaultBox 304?

Cosari VaultBox 304 Detail

Impervious to Stains & Odors

Unlike polypropylene and Tritan plastics that develop microscopic pits and permanent orange grease rings, 304 stainless steel stays showroom-clean for life.

Maximum Food-to-Footprint Ratio

Single-wall brushed steel and a flat lid eliminate bulky hollow plastic dividers and protruding utensil slots—giving you 35% more usable food capacity.

Mold-Free Removable Gasket

Permanently glued seals trap dirty dishwater. Our crimson food-grade silicone ring pulls out effortlessly for 100% sanitary cleaning.

Cosari VaultBox 304 vs. Ordinary Alternatives

Cosari VaultBox 304Standard Competitors

FeatureCosari VaultBox 304Standard Competitors
Overnight Tomato Sauce & Turmeric CurryWipes spotless in 10 seconds (304 Stainless)Permanent orange stains & lingering garlic odor
Commuter Bag Tilt Test with Salad Dressing100% dry (360° crimson gasket + 4 latches)Weeps through elastic straps or unsealed metal lids
Usable Interior Meal Volume100% open rectangular volume with rounded cornersLoses 30% space to bulky dividers & lid cutlery slots
Fridge Organization & VisibilityFlat clear lid stacks flush & shows food instantlyOpaque metal lids or wobbly domed plastic tops
Gasket Hygiene After 60 WashesRemovable red silicone ring prevents hidden moldFixed seals trap moisture & warp in dishwasher

What's Included

In the Box
  • 1 × Cosari VaultBox 304 Brushed Stainless Steel Base (Rounded-Corner Single Compartment)
  • 1 × Crystal-Clear Shatter-Resistant Flat Lid with 4 Scalloped-Edge Snap-Lock Latches
  • 1 × Removable 360° Deep-Channel Crimson Food-Grade Silicone Sealing Gasket
Technical Specifications
  • ['Base Material', '304 (18/8) Food-Grade Brushed Austenitic Stainless Steel']
  • ['Lid & Latch Architecture', 'BPA-Free Transparent Flat Lid with 4 Scalloped-Edge Snap-Lock Side Latches']
  • ['Sealing Mechanism', 'Removable 360° Deep-Channel Dark Red Food-Grade Silicone Compression Gasket']
  • ['Graduated Capacities', '220ml (Snack) / 600ml (Standard Lunch) / 1500ml (Meal Prep) / 2900ml (Family Batch)']
  • ['Interior Geometry', '100% Unobstructed Single Rectangular Compartment with Easy-Scoop Rounded Corners']
  • ['Thermal Rating', '-20°C Freezer Storage to +120°C Sanitizing Dishwasher Safe (Remove Lid for Oven)']
  • ['Storage Profile', 'Flat-Lid Vertical Stacking When Full; Tapered Nesting Bases When Empty']
  • ['Warranty & Trial', '30-Day Money-Back Guarantee + 2-Year Latch & Gasket Replacement Coverage']
Care & Safety
  • Pro Tip for Effortless Latching: Press gently on the center of the clear lid with your palm while clicking the 4 scalloped latches shut or open—this compresses the thick red silicone gasket evenly without straining your fingernails.
  • Heating & Cleaning Note: Both the 304 steel tub and removable gasket are dishwasher-safe. Always remove the clear plastic lid before warming food inside an oven.
  • Backed by our 30-Day Money-Back Guarantee & Full Cosari Warranty
  • Customer Support: support@buycosari.com
In the Box Cosari VaultBox 304

From Sunday Meal Prep to Commuter Tote in 3 Steps

Swipe left for steps 2 and 3

  1. Step 1: Pack Without Space Limits
    1

    Step 1: Pack Without Space Limits

    Load proteins, grains, salads, or fruit into the wide-mouth brushed 304 stainless steel base—every millimeter is usable food room.

  2. Step 2: Press & Click All 4 Latches
    2

    Step 2: Press & Click All 4 Latches

    Set the crystal-clear lid in place, press lightly in the center, and snap down the four scalloped-edge latches over the crimson silicone seal.

  3. Step 3: Stack in Fridge or Toss in Your Bag
    3

    Step 3: Stack in Fridge or Toss in Your Bag

    Stack multiple sizes neatly on your refrigerator shelf or slide them straight into your commuter bag with 100% leak-proof confidence.

Verified Customer Reviews

What 200+ Verified Buyers Say About the Cosari VaultBox 304

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4.8
Based on 247 verified reviews
5 Stars
212
4 Stars
25
3 Stars
7
2 Stars
2
1 Star
1
97% of buyers recommend the Cosari VaultBox 304
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✓ Verified Purchase
Megan R.2025-02-18

Use mine every single day

I use these daily for lunch and snacks, and coworkers are always asking where I got them. The brushed silver finish with the dark red gasket looks sleek without feeling boring.

Verified Purchase · Portland, OR · Cosari VaultBox 304

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✓ Verified Purchase
Carlos M.2025-01-29

Easy for the whole family

The four scalloped latches are simple enough for my kids but still close securely. We use the 220ml for their snacks and the 1500ml for adult lunches. Really practical set.

Verified Purchase · Austin, TX · Cosari VaultBox 304

✓ Verified Purchase
Jenna P.2025-03-07

Great school lunch box

Bought the 600ml for my daughter's school lunch and the size is just right. She can open it herself, and the clear lid lets her see what I packed immediately. Definitely recommend it.

Verified Purchase · Raleigh, NC · Cosari VaultBox 304

✓ Verified Purchase
Tara L.2024-12-14

Perfect for packing variety

My daughter likes a little bit of everything at lunch, so I stack the 220ml and 600ml boxes on their flat clear lids. They stay neat and fit much better in her lunch bag.

Verified Purchase · Madison, WI · Cosari VaultBox 304

✓ Verified Purchase
Nathan B.2025-02-02

Useful range of sizes

I really like having 220ml, 600ml, 1500ml, and 2900ml options instead of several nearly identical containers. The heavy-gauge brushed stainless steel feels solid and much better made than our old plastic set.

Verified Purchase · Denver, CO · Cosari VaultBox 304

✓ Verified Purchase
Erin S.2025-03-21

Holding up beautifully

After months of daily use and washing, the brushed steel base and thick red silicone ring still look nearly new. Unlike our plastic containers, nothing has warped or picked up permanent food stains.

Verified Purchase · Columbus, OH · Cosari VaultBox 304

✓ Verified Purchase
Marcus T.2025-01-11

Plenty of room for bigger meals

I train most evenings and need a substantial lunch plus an afternoon snack. The 1500ml and 2900ml tubs have the capacity I need, and all four side latches keep the single open compartment securely closed.

Verified Purchase · Phoenix, AZ · Cosari VaultBox 304

✓ Verified Purchase
Amy K.2024-11-26

Ideal for my work lunch

The 600ml is perfect for a lighter everyday lunch, while I grab the 1500ml when packing more. Both slide cleanly into my work tote without taking over the whole bag.

Verified Purchase · Boston, MA · Cosari VaultBox 304

✓ Verified Purchase
Danielle C.2025-02-25

No more stained, leaky plastic

I was tired of plastic boxes staining and leaking in my bag. The 304 stainless steel base stays clean, and the dark red gasket with four snap-lock latches has finally stopped the leaks.

Verified Purchase · Sacramento, CA · Cosari VaultBox 304

✓ Verified Purchase
Greg H.2025-03-12

The inside is actually usable

Other bento boxes lose space to built-in utensils and ice packs. This one has an open rectangular steel interior, a flat clear lid, and rounded corners, so every bit of the stated capacity is usable.

Verified Purchase · Nashville, TN · Cosari VaultBox 304

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Frequently Asked Questions

Is the Cosari VaultBox 304 truly leak-proof for thin salad dressings and juicy fruit?

Yes. Unlike 2-clip plastic boxes or unsealed metal tins, the VaultBox 304 uses a deep-channel dark red food-grade silicone compression gasket paired with four scalloped-edge snap-lock latches (one on every side) to create a 360-degree liquid-tight seal.

Which of the 4 sizes (220ml, 600ml, 1500ml, 2900ml) fits my routine?

The 220ml size is ideal for berries, nuts, dips, or toddler snacks; the 600ml size fits a standard sandwich, salad, or kid's school lunch; the 1500ml size holds a full adult commuter meal or high-calorie athlete prep; and the 2900ml size handles multi-day family batch prep.

Can I put the stainless steel base and clear lid in the dishwasher and freezer?

Yes. The 304 (18/8) stainless steel tub is 100% dishwasher-safe and freezer-safe down to -20°C without cracking or warping. We recommend placing the clear lid on the top rack of the dishwasher.

Does the dark red silicone gasket come out for deep cleaning?

Yes. The crimson silicone sealing ring is designed to lift easily out of its perimeter lid channel so you can rinse underneath it and prevent trapped moisture or mold—then press it right back in.

Are the 4 side latches hard to open or hard on fingernails?

No. Each translucent latch features a curved, scalloped lever edge for comfortable finger grip. Because the silicone gasket is extra thick, simply press down lightly on the center of the clear lid with your palm while clicking the latches open or shut.

What if it leaks or doesn't fit my lunch bag? How does the guarantee work?

Every order is backed by our 30-Day Money-Back Guarantee. Pack your sauciest meals and carry the VaultBox 304 in your work or school bag for a full month—if you aren't thrilled, return it for a full refund.

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