Manual, Moisture/Density Hammer meets AASHTO Specs. It incorporates a 10 lb (4.5kg) weight and a drop of 18" (457mm) with a 2" (50.8) face. Guide sleeve has four vent holes in each end of sleeve to release built-up air pressure. Machined steel, plated for rust resistance. Features resilient rubber ball handle. AASHTO T180. Shipping wt. 18 lbs. (8.3kg)