Universal Security Instruments USI-5204-6CC 120-Volt AC/DC Wired-In Ionization Smoke and Fire Alarm with Silence Feature, 6-Pack Take this opportunity to purchase a 6-Piece contractor bulk pack and replace all your existing smoke alarms that are over 10-Year old. Interconnect up to 18 units, 12 smoke alarms maximum; when one alarm goes off all units sound their alarm The alarm has a silence feature, which is a convenient silence button with automatic reset, allows you to temporarily override the alarm. This is ideal for cooking some and fireplaces. Eliminating nuisance alarms Optional tamper-resistant feature deters removal of alarm from bracket. The alarms utilize a 5-5/8-Inch mounting plate, which can be mounted to any standard rectangular or octagon junction box and is large enough to cover drywall cutouts Audible low battery indicator; alarm and power test buttons. Includes a 9-Volt super heavy duty battery to power the alarm in the event of an AC power failure Full-size plastic dust cover protects the smoke alarm form spray applications, dust and other contaminants thereby eliminating the need to remove the alarm during home renovation or construction