Nalgene™ sterile disposable flasks reduce the chance for cross contamination. Ideal for shaker and suspension cell culture, media preparation or storage. Made of light, crystal clear PETG (polyethylene terephthalate copolyester) plastic. Molded-in graduations. Leak-proof high-density polyethylene screw closures open to vent with 1/4 turn. Flasks are Individually packaged for easy storage and handling.