Morris Products 20902 Tefzel Cable Ties For Plenum Areas, 3-3/4" Length, 0.09" Width, 18lbs Tensile Strength, Max Bundle Diameter (Pack of 100) Tefzel fluorpolymer for low smoke emissions in plenum (air circulating) applications Minimum tensile strength of 18 lb. Maximum bundling diameter of 1.19" Plastic locking pawl for closure Meets UL 94V0 standard for flammability