The cap is molded with a deep internal lip that fits snugly against the interior wall of the tube thus preventing the contents from coming in contact with the seal or threads. In the silicone O-ring version, tubes and caps are made of polypropylene.
All tubes and closures are manufactured in a clean environment. Tubes and screw caps are made of heavy wall construction and are built to last. Non skirted tubes withstand high speed centrifugation up to 20000×g, skirted tubes up to 17000×g.
