Place washer on Knob; insert through thin section at top of post, through wide end of the Positioning Arm and then through the thick section of the Post. Attach the silicone rubber washer and reattach the Lever. Knobs are 2" Diameter X 1" Length. Unlike earlier versions with mild steel hanger bolts pinned through the wood, this new version uses a 1/4":20 hardened socket Head Cap Screw pressed through and bonded to the bolt with Cyanoacrylate. Always use a 1/4" washer with these knobs.