Free Shipping and BOPIS


Model # 21008051

Internet # 100051755

Store SKU # 182262

Battery Operated Ionization Smoke Alarm

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

$4.98 /each




Model # 21008051

Internet # 100051755

Store SKU # 182262

Store SO SKU # 198092

The Kidde i9040 Battery-Operated Ionization Smoke Alarm is a single-station alarm with an early warning signal. This alarm utilizes ionization sensing technology to activate in the event of a smoke or fire incident and its compact, 4 in. design lends it a discreet profile in your home or business. Powered by a 9-Volt battery, this smoke alarm will protect you, your family and home during a power outage. When the battery begins to lose power, a low-battery alert will begin to chirp to notify you it is time to replace.

  • Utilizes ionization sensing technology to detect smoke or fire
  • Provides an early warning signal in the event of a smoke or fire incident
  • Wireless technology for easy installation
  • Low-battery indicator chirps to alert you to change the battery
  • Test button tests the unit's electronic circuitry, horn and battery function
  • Battery power means protection during power outages
  • 9-Volt battery included use Kidde power supply (205976052)
  • Compact design for a low-profile presence

  • Note: product may vary by store

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 Sensor Type 
Alarm Type 
Alarm/Detector Features 
No Additional Features 
Commercial / Residential 
Commercial / Residential 
Connector/Contact Type 
Power Source 
Voltage (volts) 
Warranty / Certifications
Certifications and Listings 
1-UL Listed 


Rated 4.1 out of 5 by 37 reviewers.
Rated 5.0 out of 5.0 by Smoke alarm Excellent product, easy to install would recommend August 25, 2015
Rated 5.0 out of 5.0 It could save your life! I purchased these on an impulse buy. I was walking down the water heater isle and saw these at such a great price. I figure I should pick up a few and install them throughout the house. I install them that weekend and forget about them. A few months later, I'm in my bedroom and I hear a loud beeping coming from downstairs. I go to investigate and find my living room full of smoke. The smoke was caused by frayed wires on a home entertainment system. If it wasn't for this alarm, the smoke would go unnoticed leading to an actual fire. At this price, I would say to buy one for your friends and relatives as well. There aren't many gifts that you can give that can save someones life. April 10, 2013
Rated 5.0 out of 5.0 by Easy to Install These smoke alarms replaced identical items, so I did not have to reinstall the bases. July 21, 2015
Rated 5.0 out of 5.0 by Great Value!!! I've only had them installed for about 2 weeks. Easy to install and tested loud enough, for the price I think they are a good deal. So now we just have to hope and pray that they work like they're supposed if we ever have a fire in our home. November 10, 2015
Rated 5.0 out of 5.0 by Works fine, low cost, smaller than old unit Only negative is that it doesn't cover the spot on the ceiling where the old one was. Wish they'd make it bigger. Obviously, it's a replacement so most people will have the same problem. But it works just fine. November 10, 2015
Rated 5.0 out of 5.0 by Works perfctly for intended use Easy to install and others think it is loud when it goes-off, that's the point, it doesn't bother me at all. October 27, 2015
Rated 5.0 out of 5.0 by Excellent value I have installed more than 10 of these in several locations and they have been in service for over a year now. These run on single 9V battery which is included with the package. These are UL listed so meet the required standards. I really don't see the point in buying the more expensive ones unless you need dual power supply i.e. the 120V and 9V. July 16, 2012
Rated 1.0 out of 5.0 by Please Enjoy Flashing Red Light From the Manual: "FLASHING LED LIGHT: This smoke alarm is equipped with a flashing red indicator light. The light is located under the test button and will flash every 40 seconds to indicate that the smoke alarm is receiving power." September 9, 2015
  • 2015-11-25 T11:44:56.663-06:00
  • bvseo_lps, prod_bvrr, vn_prr_5.6
  • cp-1, bvpage1
  • co_hasreviews, tv_37, tr_37
  • loc_en_US, sid_100051755, prod, sort_default
2 >>