18650 Rechargeable Battery 9900mAh 3.7Volt Li-ion Batteries Button Top 4 Pack for Flashlights Headlamps

They are working pretty good so far.

Easily replacing previous solar lantern batteries. Same size. A little high Mah. So far working well

Yes, they are batteries. No, you should not buy them. There are much better batteries on the market. I bought these to rotate in a hand held garage LED light. If you know the energy density of this chemistry, you know that 9900mAh in an 18650 form factor is a bald faced lie. I knew this but for the price had hoped for 2000-2500mAh. My light lasts about 45 minutes with these while the original battery lasted 4 hours, so I decided to capacity test them on a DL24P load tester. I used a very low discharge rate of 0.1A to give them the best chance. Results were 652mAh, 926mAh, 753mAh and 1001mAh. That's right, less than one tenth of the advertised capacity. Pathetic. One of them even has a self discharge rate so high that if it sits on the shelf overnight after being charged, it is dead already.

We found these to be a little wider than the 18650 battery that they're meant to replace. So they worked well in some of our flashlights but they wouldn't fit in others. All of them use 18650 batteries and had Energizer and some other brands in them before non-rechargeable. They just don't fit in everything.

Heading lamp batteries. Good value.

Great value for Lithium ion batteries of this size and mAh rating. It is about a $1.00 more per battery than a AA Lithium ion battery.

Work wellThank you

Looks great works great time will tell how long I guess