Monobloc axle mounted discs have a friction ring and hub cast in one piece. There are two types of discs that use a friction ring bolted to a separate hub. One type has a single-piece friction ring; another has a two-piece friction ring bolted together and then bolted to the hub. Monobloc discs are available in diameters from 380 mm to 710 mm (15 to 28 in.); split discs are available in diameters of 457, 533, and 686 mm (18, 21, and 27 in.). Disc designs are also available in wheel-mounted disc applications where a monobloc is bolted to the outside of the wheel flange. These designs can vary from 610 to 711 mm (24 to 28 in.) outside diameter at varying disc thickness.