This is a replacement Arrma 13T Straight Cut Main Input Gear, intended for use with the Arrma Typhon 6S BLX. 
 
Features:
Constructed from hard-wearing steel for long-lasting durability and consistent performance
Straight-cut tooth profile
13 precision manufactured gear teeth for smooth operation in extreme RC conditions
Uses ARRMA Safe-D keyed fit to Input Shaft Cup and composite sleeve for a more secure fit
Note: Must be combined with the ARA310441 - MAIN DIFF GEAR 43T STRAIGHT, ARA310976 - INPUT SHAFT CUP SLEEVE and ARA310977 - INPUT SHAFT CUP (SAFE-D).