EASY INSTALLATION - Just remove the original bolt and headset cap, install the metal base with M6X35mm bolt, insert the AirTag, press the cap into the base, then lock the cap with three M3 bolts on the base. IP67 WATERPROOF - Waterproof design with 2 rubber sealing rings inside effectively protects AirTag from dirt, mud, sand and water. No need to worry about water leakage during rain or washing the bike. ANTI-THEFT AIRTAG BIKE HOLDER - Thanks to the screw locking design on the metal base, the cap is locked into the base tightly, which keeps AirTag stay in place and prevents AirTag from being removed easily by the thieves. SOLID CONSTRUCTION - Consisting of aluminum alloy bottom base and polyformaldehyde top cap, this AirTag case is tough and durable. It fits AirTag snugly and doesn’t impact the signal. The discreet black cap blends in well with the bicycle. HIDDEN AIRTAG HEADSET MOUNT - Elegant solution to attach AirTag in an inconspicuous location on your bike (AirTag not included). Suitable for bicycles with a headset tube size of 1-1/8"& 1-1/4". Please check your headset tube before purchg.