1. Seal type: The full-length zipper is the main closure. Even with a leak-proof zipper, there is still a tiny gap between zipper teeth. It stops liquid, body fluid and most odor, but air can slowly pass through. Heat-sealed seam areas are liquid-proof, but not designed for vacuum airtightness.
2. Truly airtight versions: Special custom airtight body bags exist (usually with extra sealing flaps or heat-sealed closure instead of only zipper). They are used for highly infectious remains, biosafety cases, to prevent airborne pathogen leakage. These are less common and more expensive.
3. PEVA regular body bag (your main product): ✅ Liquid leak-proof ✅ Good odor containment for normal use ❌ Not airtight

Simple sentence for customer reply

Standard body bags are liquid-tight and odor-resistant, but not airtight. Airtight style is available as a special custom option for biohazard infectious cases.