These sockets are available from 19 mm across flat to 80 mm across flat and 3/4" across flat to 4" across flat and 21 mm across flat to 52 mm across flat and 3/4" across flat to 2. 11/16". The outside diameter at the socket end consists of a hex across flat portion and the outside diameter on the drives end consists of splines. These are available in standard and deep lengths.