I received these SunLabz NiMH 9V rechargeable 4pk of batteries in exchange for my my unbiased honest opinion. The batteries arrived quickly with prime shipping and are uncharged, fully dead. I do not have a SunLabz charger yet but I do have a charger that charges AA and 9V. They fit nicely in my non SunLabz charger and are charging up. These will come in handy for many things including smoke detectors and childrens toy items usually need AA or 9V. This 4pk is worth every penny since when I buy disposable 9V batteries from my local pharmacy it cost me almost $4 for a 2 pk and they are generic lating not long in my TENS unit. The TENS unit takes 9V batteries and I am always in need of batteries for it since it gets used repeatedly for some pain issues in my back and shoulders. I will be able to reuse these repeatedly without needing to repurchase batteries. i am so happy.