[High volume electric bicycle horn]-- The maximum sound output reaches 120 decibels. This powerful horn is effective in alerting pedestrians and surrounding drivers in noisy environments or complex traffic conditions, helping to prevent accidents. [Anti-theft alarm]-- Press and hold the left button (locking button) to activate the alarm system. If the bike is touched or moved, the alarm will emit a loud, continuous sound to deter potential theft. Press the right button (unlock button) to deactivate the anti-theft mode. [Long battery life]-- The integrated horn has a 250 mAh battery capacity. It fully charges in 0.5 hours, supports 1000 to 1500 recharge cycles, and operates for 20 to 30 days on a single charge, providing reliable long-term use. [Waterproof IPX4 and USB charging]-- The horn is waterproof and suitable for use in rainy conditions. It features USB charging and can be charged using various power sources such as wall outlets, power banks, or laptops. [Easy installation]-- No complex tools required. Simply secure the elastic and durable silicone strap around the handlebar. Compatible with handlebars with diameters between 22.2 mm and 31.8 mm, suitable for bicycles, electric scooters, mountain bikes, and road bikes.