These Erlenmeyer Shaker Flasks are made of polycarbonate, PETG, or styrene/butadiene (Jumbo Flasks only). The polypropylene screw caps are vented with 0.2µm membranes to increase air transmission and enhance cell growth. The mouth size conforms with international SBS standards, for quick, secure connection to bioreactor equipment. Polycarbonate Flasks and Jumbo Fernbach Flasks have baffled (ribbed) bottoms to provide increased oxygenation and mixing efficiency, even at lower shaking speeds. All flasks, regardless of size or material are individually wrapped and gamma sterilized to SAL 10-6, and are free of RNase, DNase, pyrogen m endotoxins and human DNA.