DELRIN REPLACEMENT FOR THE STOCK 3D PRINTED SUPPORT. THESE WILL NOT USE A STANDOFF IN BETWEEN THEM, THEY HAVE THREADED HOLES FOR ALL SCREWS. YOU WILL REUSE THE COUNTERSUNK WASHERS AND THEN USE THE HARDWARE THAT COMES WITH THESE. THE BLACK BUSHING IS FOR THE TOP SCREW. IT GOES BETWEEN THE SIDE PANEL AND THE ALUMINUM. WHEN USING SHOCKS ON THE WHEELIE BAR, THE TOP SCREW IS OPTIONAL. YOU CAN USE IT TO CONTROL THE TRAVEL, OR YOU CAN CONTROL TRAVEL WITH LIMITERS ON THE SHOCKS AND THEN NOT USE THE TOP SCREW. SOLD AS A PAIR WITH HARDWARE.