Medical Grade Silicone replacement tubing for your Handkit, fits both Hands-Free and Standard models. This tubing also replaces the older clear Vinyl tubing that came with older models and other brand Vaporizers. Inner Diameter – approx. 5/16″ = .313 in.Outer Diameter – approx. 7/16″ = .438 in.Thickness – approx. .063 in.Comes in approximately 3 ft. and 5 ft lengths Note: This tubing will NOT fit Vapir, Vaporfection or Natural Goods products.