Chunshop 120db Personal Protection Loud Safety Panic Attack Security Rape Alarm Keychain Protect yourself against intruders/attackers,Ideal for night shift workers, elderly, disabled, joggers, and those traveling alone In case of emergency, pull out key-ring metal pin to activate siren(120db)and draw attention of police or passerby When key-ring metal pin is inserted back into the alarm, it will stop sounding To change battery: When the alarm sound goes low, please remove screws from back cover and replace 1 x 23 mA 12 V battery . Color: Black, Yellow,Powered by 1 x 23 mA 12V battery (Included ),Size: approx.4.6cmx3.8cmx1.7cm/1.81''x1.49''x0.66'',