first generation: 1. Material: aluminum alloy+ABS plastic 2. Applicable to: bicycles, folding bikes, mountain bikes 3. Ringing tones are crisp and loud, with simple appearance 4. Suitable for handlebar pipe diameter between 21-23 mm, easy to install 5. You can put the tracker in the bell to find the bike at any time 6. Weight: 23 g 7. Size: 36 x 61mm 8. Note: only the bell, not the tracker