Free Shipping and BOPIS


Model # 21009720

Internet # 203728677

Store SKU # 151533

Worry Free 10-Year Lithium Ion Battery Operated CO Alarm with Digital Display

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

$44.97 /each




Model # 21009720

Internet # 203728677

Store SKU # 151533

Store SO SKU # 198092

Kidde 10 year Worry Free Carbon Monoxide Alarm will provide you and your family with a loud warning signal against the dangers of elevated carbon monoxide levels in your home. This alarm features a digital read-out that will provide you and your family “at a glance” real-time readings of carbon monoxide levels in your home. No more waking in the middle of the night to the dreaded midnight chirp when you install this Worry Free alarm that is powered by a ten year sealed long-life lithium battery. With this alarm monitoring your home for carbon monoxide you and your family are protected from the dangers of the silent killer, even during power outages.

  • Kidde 10 year carbon monoxide alarm is maintenance-free; never replace a battery during the alarm's operating life, in addition to the benefit of maintenance free, batteries are sealed, no need to Worry about them being removed
  • Features an end-of-life signal that alerts you when it is time to replace the alarm; signal chirps every 30 - 45 seconds when alarm needs replaced
  • Money savings, no batteries to buy and replace every six months, save up to $40.00 over the life of the alarm
  • Alarm is equipped with test – reset button, tests the circuitry and horn and resets memory after alarm has sounded
  • Alarm is UL listed and is equipped with a piezoelectric horn that is rated at 85 dB at 10 ft. and electrochemical sensor that last 40% longer than other carbon monoxide alarms

Info & Guides

You will need Adobe® Acrobat® Reader to view PDF documents. Download a free copy from the Adobe Web site.


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


Rated 4.5 out of 5 by 41 reviewers.
Rated 4.0 out of 5.0 by Quick and easy Obviously, I cannot test the unit by filling the house with carbon monoxide so, primarily, my review deals with installation and appearance of the unit. It's a trivially easy install. Remove the back mounting plate (you'll need a small, electronics size flat head screwdriver for this, there is a small tab you need to release to get the plate to slide off fully), make sure the plate is level and mark drill points. You'll want to drill holes slightly smaller than the plastic inserts (included) which hold the screws in place. Unless you have a wall stud handy which I did not. Then hammer (lightly of course) the inserts into the dry wall. Screw the plate to the wall, slide the unit on and that's it. Like a smoke detector, there is a test button. Of course, you should test regularly. The alarm is quite strident and annoying and not something you'd be likely to sleep through. Which in the case of an alarm is a positive. If your home uses natural gas, at least one of these kinds of units is a good idea. It's true carbon monoxide poisoning is rare but should it happen, it's insidious. It makes one drowsy and you may think you need to get to bed. Problem being, you may not wake up. Definitely a "better safe than sorry" situation. And it's a nicely unobtrusive device. Not something that will "stick out" glaringly at all. July 29, 2014
Rated 1.0 out of 5.0 by Will Not Operate at Temperatures Lower than 68 Degrees This unit is one month old. It started chirping and flashing low battery at 4am this morning. The manual says to warm the unit up to greater than 68 degrees and the low battery alarm might go away (if not, it says to get a new unit). I'm not turning the heat on in my house in July just for this CO alarm! If the unit had a low operating temperature of 60 or less, then I could see myself giving it a higher rating, but 68 degrees is not cold. The warranty doesn't cover battery-related problems and you can't change the pre-installed lithium ion battery, so this unit is pretty much worthless to me in cooler weather. July 29, 2014
Rated 5.0 out of 5.0 by Very Nice Monitor A very impressive CO monitor. I like the digital display because you can actually see the concentration of CO in the atmosphere on the display. The 10 year battery is a great feature and ensures that your home is always being monitored for dangerous levels of CO. Installing is a breeze. Mark the hole in the wall with the base as a template drill and fasten with supplied anchors. When you slide the monitor onto the base it actuates a small switch and cuts on automatically. This is a well thought out feature that prevents it from accidently being turned off. If you have gas heat, water heater or appliances you won't find a nicer monitor to protect you and your family. April 29, 2014
Rated 5.0 out of 5.0 by Super Simple Installation - Great peace of mind. This CO detector is a great find! I like the idea that it is self-contained and does not require any batteries for it's lifespan. After 10 years, it can be replaced by referencing the installed date or the unit is designed to alert the homeowner via alarm when the batteries have been depleted and has reached end of life. The unit is shipped with the mounting plate removed. Once the mounting plate is connected with the CO alarm, the batteries start. No worries with getting a unit that has been sitting on the shelves for a year. The alarm was easy to install. It can be used as a table-top alarm, but I installed it using the two supplied drywall anchors and screws near a bedroom door. Once it was connected to the backplate - it started up and it's been monitoring since then. The digital readout is also a nice feature on this unit. You can see status on recent readings, mine has been showing "0", which is good, since it was installed. March 29, 2014
Rated 5.0 out of 5.0 by You won't find a simpler way to protect your family! I've been a firefighter for 25+ years. For all the hazards of CO, and considering how easy it is to protect yourself and your family, it's stunning how many people still don't have at least one detector in the home. This literally went up in minutes. I already have central smoke/CO detectors in the house but wanted one with a display to show any developing problem that might be indicated before the other alarms sound. November 11, 2014
Rated 5.0 out of 5.0 by SAFE AT LAST We have been needing a CO detector for years, but like many other things, it went on the back burner. What I noticed about this unit is it had everything important for safety. I like the fact that it had a 10 yr lithium battery. May 19, 2014
Rated 5.0 out of 5.0 by Easy to install and easy to read Unit has excellent visual display to confirm it's working. June 30, 2015
Rated 5.0 out of 5.0 by An outstanding CO alarm To date this has been an excellent CO Alarm. The digital display provides a clear visual indicator of any CO even if it is below the alarm threshold. I glance at the display everytime I walk by to insure the detector is still reading zero. Also, not having to worry about battery changes for ten years is a real plus. The directions are easy to follow and the CO alarm was up and running within minutes of unpacking. April 16, 2014
  • 2015-10-02T14:49:00.647-05:00
  • bvseo_lps, prod_bvrr, vn_prr_5.6
  • cp-1, bvpage1
  • co_hasreviews, tv_41, tr_41
  • loc_en_US, sid_203728677, prod, sort_default
2 3 >>