These are industrial grade duct tapes 11 mils in thickness with 39 oz/in adhesion,tensile strength of 26 lbs/in, and temp reange of 32F to 150F.  These duct tapes do not curl or twist during application, tear easily, and are ideal for heavy packaging, bundling, amd color coding.  They are also popular for duct tape wallets, purses, and the like.  They are waterproof and temperature resistant to 200oF.