First Alert Battery Powered Smoke Alarm with Silence Button – Link

Amazon has this on sale for only $6.89.

• Battery-powered smoke alarm with silence/test button
• Features convenient silence/test button, blinking power light, 85-decibel alarm
• Also includes side battery drawer and missing battery guard
• Low battery warning and tamper resistant. Sensor Type: Ionization
• 9-volt battery included, recommended battery replacement every 6 months