The ROCKBROS BT-1 is a functional bicycle bell designed with a hidden internal compartment specifically for an Apple AirTag, allowing you to discreetly integrate tracking into your bike's accessories. The bell housing is crafted from a copper alloy that produces a clear, high-fidelity sound with a long resonance to ensure you are heard by others on the road. Constructed with a blend of copper alloy and ABS plastic, this compact device measures 39 x 49 x 56 mm and is built to withstand the elements with an IPX5 water resistance rating, making it reliable during splashes or light rain. It fits standard handlebars of approximately 22.2 mm, though it is also compatible with 25.4 mm and 31.8 mm diameters. Weighing only 54g with its packaging, it provides a subtle security addition for cyclists who want to keep their tracking device hidden from plain sight.