This unusual item is a replica of the famous Al Gerhards standard hook, made out of solid Aluminum metal. This is not a working boomerang. It is not a boomalum for LD throwing. It is not tuned for throwing. It would be too dangerous to throw and the high inertia to low lift ratio would not allow a circular flight. Both surfaces are polished smooth. There are some defects in the metal. The largest defect is a black line on the underside and this can be seen in the photo below. The upper surface is almost defect free. The underside has " M = 207 gm ; W = 38 cm ; L = 61 cm ; T = 5.5 mm " etched into the surface near the lift arm tip. This boomerang replica has been part of Al Gerhards' collection for 3 decades. Please, do notthrow this boomerang. It is not a toy for children.