Novak is offering an interchangeable colored sleeves to slip onto any Novak 540-size brushless motor. Simply unscrew the end bell, keeping in mind the insulating paper and shims, and switch the existing sleeve. Compatible with all Novak 540-size brushless motors, including the Velociti Series, Velociti Light Series, SS Pro Series, EX Series, and Crawler Series. Contains one purple sleeve (for maximum heat)