Helmet Lock Helmet Holder Motorcycle Key Anti-theft Universal Key Lock Key Bicycle Security Scooter Motorcycle Medium Large Bicycle Handlebar Universal [Helmet Lock Helmet Holder Product Details] Size: 75 x 65 x 22mm Weight: 155g Material: Aluminum Alloy / Stainless Steel Color: Black Universal type, so it can be installed anywhere on a pipe section of Φ20-26mm. 22-24mm is recommended, but it can be installed on diameters from a minimum of about 20mm to a maximum of about 26mm. Packing Details: Helmet Lock Keys x 2 Hex wrench Rubber belt Since there are two keys, you can rest assured even if you lose one.