Kidde PI2010 Smoke Alarm Dual Sensor with Battery Backup for $21.97

Kidde PI2010 Smoke Alarm Dual Sensor with Battery Backup for $21.97.  Shipping is free on orders over $35.  If needed, use this Filler Tool to pad the order for free shipping.  Here is a screenshot for your reference.  It features dual sensor with both a photoelectric and ionization sensor, 120V hardwire alarm with battery backup, and Red LED flashes every 30-40 seconds to indicate that the smoke alarm is operating properly.

Kidde KN-SMFM-i Silhouette Hardwire Low Profile Smoke Alarm for $13.37

Kidde KN-SMFM-i Silhouette Hardwire Low Profile Smoke Alarm for $13.37. Shipping is free on orders over $25. If needed, use this Filler Tool to pad the order to qualify for free shipping. Here is a screenshot for your reference. It contains a rechargeable battery that runs off central electricity, Ionization sensing technology, and meets UL, NFPA, FHA, HUD, and CSFM standards.
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Kidde 9C05 & 916 Carbon Monoxide & Smoke Alarm Value Pack for $19.54 or $24.51 Shipped

Kidde 9C05 & 916 Carbon Monoxide & Smoke Alarm Value Pack for $19.54.  Select free site-to-store for in-store pickup at Walmart to save on shipping.  Otherwise, shipping is $4.97 for a total of $24.51 shipped.  Here is a screenshot for your reference.  It features a flashing green LED and front loading battery door.  Most places have it for about $37.

DuPont Self-Charging Smoke Alarm for $5.99 Shipped

DuPont Self-Charging Smoke Alarm (PS-131) for $5.99 shipped.  Here is a screenshot for your reference.  It contains a 10-year self-charging power pack which automatically re-charges from the household current when the light is on, and remains fully charged if the light is on for about 2 hours per week, and will operate for 30 days from a full power pack.  It uses an ionization type sensor to detect the presence of smoke.  It usually goes for about $10 or more.