USB Rechargeable 9V Lithium Batteries 1000mAh - 4 Pack for Smoke Detectors, Carbon Monoxide Alarms, Guitar Pedals, Flashlights & Electronic Toys - Long Lasting Power for Home Safety & Portable Devices

I've started using lithium 9v in my guitar pedals for a variety of reasons. They are lighter and smaller than (some) Ni-MH 9V's, which barely fit in the pedals. They charge very quickly, and have a fully-charged voltage that is closer to 9V than the Ni-MH batteries.One note - when I got the 4-pack, I thought 2 of them may be defective. They turned green on the top, but seemed to have no charge. Actually, I think the issue was trying to charge them with the 4-way split cable that comes with it. After charging them one at a time with a high-output USB-C charging cable (individually), they charged quickly and fully. Battery life seems pretty good - I'm not expecting that to be elite, but for convenience and cost savings, 9V's can add up in a HURRY, so this is a great option to have.