UH1-55 is a direct replacement to the stock hub that comes with all three models of the Simucube 2 family of direct drive base systems, It replaces the stock hub and adds 55mm extra length for a total of 105mm from the front face of the servo to the end of the extension, It has a smaller diameter that makes it the perfect add-on to help you extend the motor shaft and give enough clearance for you center monitor to be as close as possible to the servo axle, It is compatible both with the stock Simucube 2 quick release and with any 70 PCD quick release on the market, Both the stock SC2 QR and the 70 PCD holes are threaded M5 so no need for ugly nuts, The UH1-55 is also compatible with the SimCore ProXT modular extensions for those that need more than 105mm extra length, CNC machined out of a single 6061 aluminum billet block and anodized in black color.