The SABRE Personal Alarm is great for College Students, Moms, Runners, Seniors, Service Industry Personnel, Commuters, Nurses. Remove alarm from keychain to activate 110 dB siren. Audible up to 300" (100m). Dual siren design. Attaches to bag, backpack, keychain or purse for easy access. Requires four LR41 Alkaline batteries (included).