The Quad Coupler 1.5 will clamp from 1.25” OD to 1.5” OD tubing, as well as 1" pipe (1.315" OD.) The Quad Coupler 1.5 is 1.25" thick. The notch on the outside of clamp is 1.26" across the flats and will fit over 1-1/4" square tube, while locking the clamp parallel with the 1-1/4" square tubing. Use the flat face to bolt to a fixture, or to allow the Quad Coupler 1.5 to rotate when fastened to square tubing. The distance from the bottom of the clamped pipe or tube, to the flat or notched connecting surface, is .84" Complete with 3/8” x 1.25” socket head cap screw with nylon insert lock nut and Belleville spring washer. Minimum Size1.25" OD tube, 1" pipe, 1.315" OD pipe Maximum Size1.5" OD tube, 1-1/4" Pipe Working Load Limit770 Pounds Hardware3/8"-16tpi x 1.25" Socket Head Cap Screw. 3/8" nylon insert lock nut.Belleville Washer. Dimensions1.25" Thick Weight.5 lb. Case Quantities12 or 24