Smoke Detector, Hardwired Interconnected Smoke Detectors, Smoke Alarm With Product Features [Hardwired interconnection] Up to 12 smoke alarms can be interconnected to cover your entire home. When one detects smoke, they all make a sound to alert everyone in the house, creating an interconnected safety net for your home. [9V Battery backup] Hardwired smoke detectors are equipped with DC 9V batteries. Ensure that all units are always connected and continue to function properly, even in the event of a power failure. Low battery alarm reminds you to replace the battery as soon as possible. If an error occurs, the system automatically triggers the fault mode, prompting you to check the device. [Test Mute button and LED light] It is connected with other alarms. Just press the test/mute button on one of the units to test or mute the entire interconnected system. If the smoke alarm is in normal working condition, the green LED light is always on and the red LED light flashes every 32 seconds [Photoelectric smoke sensor] Based on advanced photoelectric technology, smoke alarms can be more sensitive, fast, accurate measurement of smoke levels. More than 85 decibels of alarm sound, you can more clearly hear the danger coming. [Simple installation] The installation of smoke alarm is very simple. The AC connector is connected only to the mains power and signal cables. (Please connect as instructed) Shipping: Shipping is complimentary within the lower 48 US States. We Do Not Ship to PO/APO Boxes, HI or Alaska We Do Not Ship Outside of the Continental US All items ship within 24-72 hours of Payment For large items that require Freight shipping a valid phone number is required to call and schedule your delivery Terms of Sale and Feedback: Feedback is extremely important to us and If you are satisfied with our transaction, please take a moment to leave Positive Feedback. YOUR Satisfaction is our #1 Priority! If there are any issues, PLEASE contact us BEFORE leaving a neutral or negative rating so that we may resolve any concerns. We PROMISE we can make you happy if you give us a fair chance. Returns / Concerns: All items qualify for returns within 14 - 30 days of receipt. Buyer is responsible for return shipping on any item that is not damaged Please be sure this is an item you want before making your purchase. Customer Satisfaction is our TOP priority! All items are IN STOCK at time of listing. Inventory changes constantly and it is impossible to maintain a perfectly accurate count of all items. Please do not penalize us if we have to issue you a refund! Thank You For Your Business!