Crest’s Sentry II Door Alarm is inexpensive yet durable. Once installed, it is virtually theft and tamper-proof. Powered by 9 V battery (not included). It requires no external wiring. Easy to install. Sentry II emits a piercing, modulating tone when door is opened. Front panel mounted key switch allows prompt alarm shut-off only by authorized personnel. Two keys included.

• Case constructed of heavy-gauge stainless steel
• Sounder available in 2 volumes
• Unique, tamperproof design
• Installs in minutes
• Automatic reset model resets automatically when door closes