It's easy to install this handsome, durable backrest on your 33 liter large SHAD Top Case. Inside the lid, the location for two screw holes is clearly marked by two small indentations molded inside the lid. Drill a 7/32 inch (or 5.5mm) hole at each of the two indentations. Place the two threaded sheet metal clips on the backrest tabs. Place one of the screws through the special SHAD washer and fully insert the screw through the hole in the lid, so the threaded end protrudes from the case. Holding the screw in place, move the backrest into place until the screw is in the threaded insert, tighten only one or two turns. Push the other screw/washer combination through the top case and engage it in the other backrest threaded insert. Tighten slightly. Then tighten both screws snugly.