EBL 9V Lithium-ion Rechargeable Batteries (2 Pack) with Smart Charger - Long Lasting Power for Smoke Detectors, Guitar Pedals & Electronic Devices

I picked these up for my TENS devices. I was sick of running through 9 volt batteries while trying to keep up with TENS therapy schedules. It's already hard enough to keep motivation going for long term stuff, and buying batteries was quickly becoming an unwelcome chore. After some poking around on Amazon these seemed like the way to go. And sure enough they perform perfectly. They charge fast. They quite frankly last longer than standard 9 volts in my TENS units. I am thoroughly satisfied with this purchase.If I had to nitpick I would say they're a tight fit. They're like the tiniest millimeter larger than a standard 9 volt. So fitting them in can be tight and removing them a little more annoying. On this note, the shrink wrapped plastic label will eventually take damage I imagine. Not that I'll forget what they are or anything. But it's mostly a non-issue in my situation. I just gotta make sure the pull ribbon is situated well.Long story short; I had a specific use. These work perfectly for it. In fact, they exceeded my expectations. I feel like I already got my money's worth out of them with the amount of cycles I've done. If they died tomorrow, I'd be disappointed but probably buy them again. Of course I have no reason to think they'll run out of juice any time remotely soon. Already saved me money, and I believe they'll continue to save me lots more.