Tube caps and closures are available in various materials, sizes, colors, and with a variety of closure types. They are also available in sterile and non-sterile formats and may be autoclavable. O-rings and cap liners, as well as other closures, may also provide leak-proof technology for use under demanding conditions. Thermo Scientific™ Screw Cap Microcentrifuge Tube Caps are autoclavable and include O-Rings to form a secure seal.