White circular smoke alarm sits flush on a white ceiling, showing the Kidde logo, a central HUSH/test button, a red indicator slot and curved ventilation slots around its face.

Photoelectric Battery Operated 4" Smoke Alarm

P9040

The Kidde P9040 smoke alarm is a battery operated smoke alarm that utilizes photoelectric sensing technology. The four (4) inch unit is smaller in diameter giving discreet design with the same quality you would expect in a Kidde manufactured product.

  • Battery Operated (9V Battery Included) – Easy installation and provides continuous protection even during power outages.

  • Test Button – Tests unit’s electronic circuitry, horn and battery function.

  • Low Battery Indicator – Low battery warning chirp alerts user to change battery.

  • Discreet Design – Four (4) inch diameter.

Helpful Resources

Upgrade to

This model is to be replaced with 10SDR

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A round Kidde smoke alarm is mounted on a ceiling, showing its vent grille, brand logo and a test/hush button with a red indicator against a white background.View Product
White circular smoke alarm sits flush on a white ceiling, showing the Kidde logo, a central HUSH/test button, a red indicator slot and curved ventilation slots around its face.
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Helpful Resources

Click on the video to learn more about how to install your Kidde Smoke alarm.

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A red fire extinguisher and three Kidde smoke/CO detectors (one boxed) stand arranged on a light wood tabletop against a pale wall, accompanied by a round "#1" safety-brand badge.

Why Kidde

As North America's #1 home fire safety brand,* Kidde has been working to help make your home the safest it can be for more than 100 years. Now, our latest smoke alarms and combination smoke + carbon monoxide (CO) alarms are bringing you the next level of fire and CO safety. Help protect what matters most in your life with features like cutting edge technology that send fast alerts to give your family more time to get out safely. And enhanced sensing technology that reduces false alarms often caused by cooking.

*Based on total household installations as of December 2023.