1/2-13X10 Timber Bolt Partially Threaded Galvanized (Pack Qty 25) BC-50160BTBG by Shorpioen

A round head bolt with a bearing surface that intersects with a shank at a 90 angle. Where the bearing surface and shank meet are four fins, 90 apart from each toher (it is an acceptable variation to have two fins 180 opposite each other). The underside of the head has a series of concentric circles. The shank is partially threaded with an unified thread pattern, and a blunt point | Used in wood and marine applications. The fins prevent the bolt from turining when set in place. The concentric rings under the head keep water from entering the bolt hole. The extra wide head diameter makes it unnecessary to require a washer