This Pinion Gear 21T 0.5 MOD CNC 2.3mm Bore is compatible with The Arrma Grom (ARA2102T1, ARA2102T2, ARA2102T3, ARA2104, ARA2104T1, ARA2104T2, ARA2106, ARA2106T1, ARA2106T2, LOS1122405, LOS1122408, LOS1122409, LOS1122412, LOS1122419, LOS1122434)