Design with small size and modern fashion look.built in boost circuit with loud sound reached 100-120 db With rechargeable 280 mAh lithium battery,used more convenience .USB cable charge 1.2 hours full charge. Contains USB cable,1.2 hours full charge.one charge have 2000 times ring bell can work about 20-30 days Have 4 sound modes,whistle sounds,horn sounds,alarm sounds,tram sounds,dust resist,IP 65 waterproof level Easy to install:put the silicone strap fixed on the handle.suit for 0.86"-1.25"(22.2-31.8 mm )diameter bicycle handlebar Specification: Name: bicycle electric horn Color: Black Material: ABS+PC Weight: 40 g DB: 100-120 DB Charge input: 5V-250 mAh Waterproof level: IP 65 Battery: 280 mAh lithium rechargeable battery Sounds:4 modes whistle sounds,horn sounds,alarm sounds,Tram sounds Product package: 1 pcs bicycle electric horn 1 pcs silicone strap 1 pcs USB cable 1 pcs use manual