This is Overdose 3mm Width Drive Belt. The drive belt that is standard in the rear mount kit is now available as a spare part. Made by Mitsuboshi Belting Co., Ltd., which is an OD exclusive product, it is a highly reliable product that is highly compatible with OD pulleys.
For: OD2874 GALM Ver.2 Aluminum Rear Mount Kit
Overdose 3mm Width Drive Belt (1 pc)