This is the 20 tooth Top Gear for the E-Firestorm Series. FEATURES: Direct replacement part Steel construction 20 teeth YOU WILL RECEIVE: One steel 20T Top Gear for the HPI Blitz REQUIREMENTS: Installation into transmission assembly SPECIFICATIONS: Outer Diameter: 0.46"(11.6mm) COMMENTS: For pitch information, one would need to contact the manufacturer directly. Also fits the HPI Blitz (HPID10**) lmm 11.13.09 ir/jxs &