These are Schumacher Racing Products factory replacement assembled differential knuckles for the Cat 2000 platform. Sold as a pair, each knuckle comes pre-assembled with the ball and pin hardware ready for installation. The metal construction is suited to the drive-train demands of 1:10 competition use. Set-screws are included to secure the assembly. Features: Sold as a pair Comes pre-assembled Includes set-screws Metal construction Direct factory replacement for Cat 2000 7/7/26 cs