[Product size] 36*61mm. 【Anti-theft design】 Rotate the top of the bell, we can hide the AirTag inside the bell and find the location of your bike through the network, so you can track your device anywhere. (excluding aviation tags) Waterproof design: With waterproof design, you don't have to worry about riding in the rain, it can better protect your AirTag from rain and damage without affecting the touch screen and shielding the signal. 【High-quality material】 Sturdy and durable, waterproof design prevents water vapor from entering and can be used normally in the rain. [About sound] The bicycle bell is made of aluminum alloy. The sound is loud and clear, up to 110 decibels. The sound has strong penetrating power and can remind pedestrians and passers-by very well. Wide Application: It can be used with most children's bikes, road bikes, mountain bikes, electric bike handlebars, and is ideally sized to fit almost all handlebars with a diameter of 22mm. Note: The data are all measured