1. Designed for bikes with front fork holes (Note: Tracker not included!). 2. After the tracker bracket is installed on the hole of your bikes front fork, no one but you will notice that there is a tracker inside. This effectively prevents the bike from being stolen and lost. 3. Protected from water and dust. 4. The shell is made of high-quality aluminum alloy and plastic materials, which is strong and durable. 5. Once installed on the bike, the tracker will not fall off even during a bumpy ride. 6. Applicable front fork inner hole diameter: 18-30mm