Saf-T-Seal screw cap microcentrifuge tubes are strong enough to withstand centrifugation up to 20,000 x g. Suitable for use in vapor-phase liquid nitrogen storage, -80°C freezers, boiling, and autoclaving. Deep external threads protect against sample loss and seal failure. An interior U channel in the lid keeps the ethylene propylene rubber (EPR) "O"-ring in place as the cap is tightened. Certified free of detectable RNase, DNase, and DNA. Tested pyrogen free. Graduated with etched writing surface. Autoclavable.

Mixed color packs include blue, green, red, violet, and yellow caps.

Tubes and caps are packaged in separate bags.