A new kind of ring- high-pitched ring cuts through traffic noise, while the deep harmonic adds long, clear tones Premium materials- cnc-machined 7075 aircraft-grade aluminum ringer and a strong, high-tensile stainless-steel spring is corrosion resistant Easy mounting- mount opens over the handlebar, so there's no need to slide it on; tightens with a single hex screw (Allen key included) Cable management- the cable management system gathers your cables without hindering the performance of the bell Sizing-small fits 22.2mm, large fits 31.8mm bike bars; make sure you know where you want to place the bell to choose large or small size