MTC Bio Microcentrifuge Tubes with Cap, Sterile, 1..features: sterile comes standard by electron beam radiation self-standing bag with gusseted bottom stop-pops supplied 10 cap locks in every bag sureseal s tubes are manufactured under clean room conditions, using only bioclear co-polymer, an advanced polypropylene that maximizes clarity, centrifugal strength tested up to 28,000xg and the usable temperature range -90c to +121c.