This is a security alarm with an LED light and neck strap. Model number: SE-205BS It has been tested by a public testing institution and is waterproof (IPX5) and dustproof (IP5X). The sound volume is 95db (measured 1m away), which is a loud volume and useful in emergencies. It operates on two AAA batteries, and the batteries can be replaced. It is designed to be easily attached to a school bag. [Model Number] SE-205BS [Volume] 95db (measured 1m away) [Waterproof Function] IPX5 (tested by a public testing institution) [Dustproof Function] IP5X (tested by a public testing institution) [Batteries] Includes 2 Maxell AAA batteries [Continuous Sound Time] 2 hours [Material] ABS resin [Size] 85 x 50 x 28mm (thickness) [Weight] 61g (including batteries) The outer box will be folded for shipping. Please let us know if you do not need it.