Weber Scientific Sterile Sampling Bags are sterile, single service bags made of heavy transparent polyethylene. Key Features Leak-proof and airtight Puncture-proof tabs Capacity is measured when the bag is closed, and tab is folded over 3 times; volume & dimensions are approximate Bags should not be used at temperatures above 180°F (82°C) Bags can be frozen to any temperature Write-on strips have a paper-like and smear-resistant finish and can be written on with any ordinary ballpoint pen, pencil, or marker Double round wire closures