USB Rechargeable Battery: Personal alarm siren is made of rechargeable lithium battery, not button battery. Dont need to replace the battery, directly use the usb data cable to charge and charge time is only 30 minutes, then you can get 1 years in standby130 dB Safety Emergency Alarm: With ear-piercing sound to draw others attentions even 300 yards away when youre in danger. Up to 50 mins of continuous sound to ensure emergency use. It will replace self-defense weapons to protect your safety, as pepper spray2 Ways to Use You can pull the contact pin out or press the switch 2 times quickly, to activate alarmLED Emergency Flashlight: Light bulbs are bigger and brighter than flashlights of traditional security alarmLightweight & Portable Alarm Keychain: Self defense alarm can be attached to purse, backpack, keys, belt loops, and suitcases. It also can be brought onboard a plane, really convenient, fit for Students, Joggers, Elders, Kids, Women, Night workers.