Although sold on "Best Before" date the battery works perfectly. I only wanted it for the sensor in an electricity monitor to see what was using electricity in the background so don't need it to work for months. At £1.99 it was just what was needed. The monitor isn't sensitive enough to accurately pin point offending items as, anything up to about 5w shows as 0w. Anything above that shows a minimum of 49w. I'm glad I didn't need to spend any more!