This is a replacement Arrma Kraton EXB 43T Spiral Cut Main Diff Gear. This is a replacement for the Kraton 6S EXB model, but can be used with the standard 6S BLX Kraton, Mojave, Notorious, Outcast, and Talion kits as an optional upgrade.NOTE: Must be used with ARA310979 - MAIN INPUT GEAR 1..