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.