I purchased 3 of these 9 volt rechargeable batteries as I use them in a a stun gun. When I bought alkaline, the battery would run out of power in a few weeks. So, since these can be recharged 100 times, I save money by charging them overnight. It takes about 7 hours. I used to use RayOvac but RayOvac is slightly larger and would barely fit into my stun gun (RayOvac also used to be sold on amazon.com). Energizer is regular size & fits just right with 8.4 volts (8.4Vcc) NIMH. Some rechargeables are just 7.4 volt, so be careful what you purchase. By the way, it has been increasing harder to find rechargeable 9 volt batteries in supermarkets (and I live in Seattle), so I turned to amazon.com, and found what I needed. They also seem to hold a charge longer then the RayOvacs. They are made in China for a company in St. Louis, Missouri. UPC # is 0 39800 00916 6.