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Model # 21010408-N

Internet # 205465967

Store SKU # 1000535877

Worry Free Hardwired Combination Smoke and CO Alarm with Voice and Lithium 10-Year Battery Back Up (3-Pack)

This item has been discontinued.
The Home Depot no longer carries this specific product.

$165.00 /package



Model # 21010408-N

Internet # 205465967

Store SKU # 1000535877

Kidde Hardwired-Interconnected 10 Year Combination Smoke and Carbon Monoxide Alarm feature 2 sensors in 1 unit. The alarm is suitable as a single station and/or multiple station (24 devices) alarm. This alarm contains a 10-year lithium battery backup, removing the need to replace batteries in a hardwired unit and carries a limited 10 year warranty.

  • 120 Volt ACDC
  • Sealed lithium battery backup
  • Voice warning
  • Peak CO level memory
  • Peak level memory
  • Interconnected

Info & Guides

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Product Depth (in.) 
Product Height (in.) 
Product Width (in.) 
Alarm Sensor Type 
Alarm Type 
Carbon Monoxide,Smoke 
Alarm/Detector Features 
10-Year Battery,Battery Back-Up,Hush Feature,Interconnected,Tamper Resistant,Voice Alert 
Commercial / Residential 
Commercial / Residential 
Connector/Contact Type 
Power Source 
Voltage (volts) 
Warranty / Certifications
Certifications and Listings 
1-UL Listed 


Rated 4.2 out of 5 by 37 reviewers.
Rated 5.0 out of 5.0 by great product once you figure out installation buying this in a 3pack really saved money. I got these to replace ones by the same company that needed batteries replaced annually. I called the manufacturer to see if I could insert these onto the existing bases on the ceiling and they said yes. Not exactly! You need to use the new bases to activate the 10 year battery. The old bases will not do that and when you plug them into power, they will keep saying 'low battery'. You can actually mount them on the old base but before you do, you need to activate them using the base included with the new detector. The activation procedures are buried in the middle of the multilanguage instructions! December 17, 2014
Rated 5.0 out of 5.0 by Finally a smoke detector that does it all Nice to have all the necessary features in one unit. They remove the need for multiple types of detectors. I did receive one unit that failed, customer service was very helpful in determining that and then sent me a new one, no charge. When installing do note that if the connection is not wired perfectly it will trigger all the alarms on the circuit and not shut off no matter how many times you press the cancel button; so to be sure I suggest you strip off more of the wire's sheeting to give you ample wire to wrap around the electric supply. I use one of these next to a wood false alarms. May 26, 2015
Rated 1.0 out of 5.0 by Not so pleased I bought three units (wired & sealed battery) to replace some expired Kidde alarms I had in my house for about 7-8 years. They installed easily as the mounting brackets and the electrical connectors were unchanged -- that was unexpected but totally ok with me! About a week after installation, one of the 3 units started chirping its low battery alert. Remember, these are sealed batteries that are supposed to be good for 10 years; the manufacture date per markings on the unit was 5 months ago. The issue is unresolved and I found hitting the silence button makes it quiet for a while. I'm quite disappointed and I've had to silence it numerous time now. March 10, 2015
Rated 5.0 out of 5.0 by Good product We replaced older models, with a different connector, so it was necessary to turn to power off. That said, aside from the time required to drag out and set up the ladder, and locate the screwdriver, the installation itself took less than 5 minutes. Very easy installation and easy testing. Also, when wood stove smoked up house a bit one day, the alarm (upstairs!) worked perfectly. Since proper location of this alarm puts it in a spot overhanging the base of a staircase, and we don't want to have to climb to that location often, the 10 year battery is perfect. So happy it is available, and the product is wonderful! April 21, 2015
Rated 5.0 out of 5.0 by Bought individually instead - cannot buy 3-pack in-store. Was picking up on a trip. Not readily available in Canada. Only available pre-ordered and shipped to home or for pickup in-store. Was not able to order for in-store pickup in time, so I had to pay more for them packaged individually in-store. Also needed 4 and not just 3. I needed to replace them all in the house due to expiry. Permanent battery and 120V AC makes this design 'worry-free'. Easy to install and setup - fit on the mounting plate and plug from the old Kidde units. Comes with a new plug harness to replace any damaged or questionable ones. Did not see any tab to remove to activate built-in permanent battery so it must be 'on' when mounted? I will have to test units with the AC power off to confirm this. A little more costly but worth it to avoid the inconvenience of having to replace the battery regularly due to very high ceiling and stairway locations. A good buy. May 12, 2015
Rated 5.0 out of 5.0 by Good buy, pretty easily installed After a few minor installation issues, all three units are in and operating. Here's what I wish I knew to expect when installing them: 1. I installed one of the new devices, restored power (planning to test that one before installing the other two) and it immediately sounded the alarm. After re-reading the instructions, I realized that all three had to be connected before testing. 2. In my case, two of the devices were in an error state initially after power up. Running the test cycle cleared it, but only on that one device. The "a-ha" moment was when my partner suggested running the test on each device. That got all of them running in their normal state. 3. Installing the devices onto the ceiling mounting ring takes a very firm twist - firm enough that I was concerned about cracking the plastic, but that's what was needed for all three devices to get them to engage. January 5, 2015
Rated 5.0 out of 5.0 by Dependable Product This is my second time I purchase this product ( 10 years ago). It is made to last for ten years and it did. Believe it or not the warranty it had was true. It went ten years later. great product but pricy but worth every nickel. Lopez April 12, 2015
Rated 4.0 out of 5.0 by quick and easy easy to install, but needed mounting screws, otherwise they work well December 10, 2014
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