"Materials" front-end for stainless alloys and chrome plating is not rust; backend is ball-shaped elastic rubber air bag, squeeze out when, breathing recovery automatically when you let go.

"Size" -19 cm total length, Bell-7.5 cm diameter, (Please note theincrease! )Speakers fixed buckle inside diameter: 2.2CM.

"Features" loud and clear sound quality, winding-look stylish, in front of the vent hole of trumpet, voice output; affordable, folding bikes, mountain bikes, city bikes can apply.