SureSeal sterile screw-cap microtubes come in a variety of sizes, cap configurations, graduation options, and now light-blocking amber. Made from ultra-clear polypropylene, these screw cap microtubes include assembled caps with silicone O-rings that assure a leakproof seal from -90°C to +121°C. All SureSeal screw cap microtubes are sterile, RNase, DNase, & pyrogen free and may be centrifuged at up to 22,000xg. Ultra-clear polypropylene Molded or non-graduated options Leak-proof O-ring seal Light-blocking amber available Sterile, RNase, DNase, Pyrogen free