D-shaped backing plate for flat platten assembly, this one with even deeper reach for slack belt grinding. Wheel mounting holes are 1/2"-13 precision tapped to ensure that axles are perpendicular to the plate. the slots for a flat platten mounting bracket are 1/4" wide & 6" apart, the u-shaped adjusting slot accepts a 3/8" bolt or stud. The axle holes are 10.5" center to center apart; if you mount two 2" diameter wheels on this backing plate you can easily mount an 8" long by 2-1/2" wide flat platten between the wheels for a large grinding surface. The rectangular spacer plate is 1/8" thick, this effectively makes this plate 1/2" thick through the pivot point & therefore interchangeable with any 1/2" thick d-plate. M10 holes in the holes for the roller are pulled in the teeth Holes are grooved include 2 grade 8 bolts, 3,5" long, with 4 nylon spacers, 2 1/2" washers & 2 half-nyloc nuts.