This is the 6537 Wire Retainers/Gear Cover 3x4mm BCS (2) from Traxxas.Traxxas has grown to become the number-1 selling name in RTR nitro and electric models for the last 4 years running.No one has done more than Traxxas to advance the RTR category with innovative thinking and fun designs that make it easy for anyone to get started in the great R/C hobby.Traxxas, truely the fastest name in Radio Control.