The RM-01 chassis is equipped with super tough spargear that has excellent precision and strength for the RM-01 chassis. Increased driving efficiency and quietness as well as smooth self-defing operation for improved repronation. The RM-01 kit standard gear ratio (4.5) with 64 pitch 20T pinion gear (PNB20 or PNC20) sold separately. Spargear can be used with 88T-100T (S64-88R - 100R) for M300 with an inner diameter of 0.4 inch (10 mm).
(From Amazon.co.jp)