To use the Mono 12mm hex wheel on the front of a T4 or T4.1 it requires JConcepts part # 2170 front Axle, #2081 clamping hex on the front and rear and Team Associated #9880 front steering block. (JCI2170 front Axle)JCI2170 (JCI2081 clamping hex adaptor front and rear) JCI2081 (ASC9880 AE inboard hub conversion)ASC9880