Check it Out! After living through a house fire I am a huge fan of smoke alarms and I just had to tell ya'll about this new Ultralife 10 year Smoke Alarm Battery that I just found out about! This 1 battery replaces 20 9v batteries! That is 10 years worth of batteries in your smoke detector. You will never have to worry about checkin them every 6 months! Over at Interstate Batteries, you can save 20% off your purchase of the Ultralife 10 Year smoke alarm battery and anything else you order when you use code: FIRE12 at checkout, now thru 10/31.