Crosby McKissick blocks have been the industry leaders for decades. Preferred by oil, gas and major construction companies. Made from alloy steel with a swiveling side plate to allow wire rope to be loaded mid line. The nut is welded in place and the bolt has a special keeper so you neither will be lost no matter how many times the block is opened. Specification & capacity information is a fixed to every block. Sheaves grooves are flame hardened for longer life.