This ISO caliper mount is pre-mitered to fit our 1-1/2" round, rear dropouts for a 10 mm axle. It will fit most seat stay diameters and angles, but may not be applicable in all cases. It is 3/16" thick with 51 mm hole-to-hole spacing and is made from 1018 steel.
Item sold individually.
Photo courtesy of 44 Bikes.