Voniko 9V Batteries 4 Pack, 9 Volt Alkaline Battery for Smoke Alarms

Customers find these 9V batteries to be of good quality and value for money, working well in smoke alarms. The battery life receives mixed feedback - while some say they last a long time, others report they don't last as long as expected. The charging level and shelf life also get mixed reviews, with some praising the high power output and 7-year shelf life, while others report low voltage and no 7-year shelf life. The beeping aspect is mixed, with some customers reporting immediate alarm silence while others experience continued chirping.