Made Form Medical Grade Silicon Rubber Which Complied With Temperature Resistant From -80 C To 250c (-110f To 480f) Non Reactive To Body Tissue And Fluid Non-adherence To Tissue. Unaffected By Most Waster Soluble Materials Sterilisable By Steam , Dry Heat Ethylene Oxide (et) And Gamma Radiation' Resists Oxidation Ozone And Radiation Indefinite Shelf Life Does Not Support Bacterial Available In Size From 6 Mm Id To 60 Mm Id.