The Crawlmaster Sport is the SMOOTHEST budget motor built for messy, dirty, off road action. Whether on the rocks or in the dirt, the Crawlmaster Sport is perfectly at home. Great choice for young drivers, running in the muck without ruining an expensive motor, or just crawling on a budget. FEATURES: 5 slot rotor for industry leading smoothness Zero timing, universal installation and rotation direction 1/8th inch shaft diameter 36mm OD x 52mm length (not including shaft) 178g weight m3 mount holes, 25mm spacing, "540" standard ball bearing on output bronze bushing on end bell High strength magnets Equivalent KV: Crawlmaster Sport 540 13t - 1850kv Crawlmaster Sport 540 16t - 1500kv Crawlmaster Sport 540 20t - 1250kv Crawlmaster Sport 550 12t - 1700kv Crawlmaster Sport 550 15t - 1250kv