Impact Atom Clamp With 1/4-3/8 Screw Adapter 1/4"-20 and 3/8" Sockets Fits 0.59 - 1.37" Pole Diameters; Fits Flat Surfaces up to 1.37" Thick Textured Non-Slip Jaw; Ratcheting Handle Supports Over 15 lb; Weighs only 4.0 oz Includes 1/4"-20 / 3/8"-16 Adapter