The Kyosho OT-131 parts bag contains 20 pieces of 5 x 8.5 x 0.2 mm shims. They featured on the Lazer ZX-R and were used to space out the bearings on the drive shafts. While not documented fully in the instructions manual, the combination of the manual and the exploded view notes the front to have 2 inner and 1 outer shim on the W-5061 axle while the rear features a shim on the inside and on the outside of the OT-18 axle.
OT-131
