The AC-AC MIRROR/ACCESSORY post clamps will fit the 5/8” Magnum kingpins, and should be used with the longer 230 mm mirror/accessory posts. The small kingpin clamp should be removed before fitting the larger accessory clamp. The clamp should fitted close to the wheel, and with the side facing up which has the greatest distance between the two holes as show left. A smaller AC-AC15 clamp is used on the 15 mm kingpins of the GT20. The mirror post is designed to accept the Mirrycle mirror, as shown.