Nest Scientific tissue culture flasks are molded from crystal clear USP grade VI virgin polystyrene. They are plasma etched (TC treated) to support adherent cell lines. Feature a vented cap with a USP grade VI 0.22uM PTFE membrane for gas exchange. Flask upper and lower are ultrasonically welded together with no adhesives that may leach. Molded in an ISO 7 cleanroom, sterile (SAL 1 X 10^-6) and lot tested free of DNase, RNAase, DNA, cytoxins/endotoxins and BSE/TSE. Extensively tested for leachables/extractables per ISO 10993. This flask is among our best selling items worldwide. ~20% of US brands on US market private label this flask from Nest. cGMP compliant (21 CFR part 820/821). Extensive validation dossier available upon request.