ENEGON 2 Pack 9V Rechargeable Lithium Batteries, 1000mAh 9000mWh with 2-in-1 USB C Charging Cable, high Capacity 6F22 Batteries for Smoke Alarms, Metal detectors, Microphones More.

One of the better rechargeable batteries. Holds charge , is easy to charge to. Comes with a nice plastic storage case to

I bought these off a 'net recommendation so I could use them to power my bass guitar preamp. When I turned on my bass preamp switch after putting one of these fully-charged batteries in, my amp emitted a sound I could only describe to you as a Pterodactyl getting a rectal exam. Seriously. I had my suspicions that I was going to get more hum but dang, now I have to clean my underpants.Still evaluating these for OTHER uses, but I wouldn't put these in a stringed instrument such as a bass or a guitar.

They work perfect for for my effects petals for my guitarthey were causing interference with my amplifier when plugged into the wall outlet they solved the issue they're perfect wherever a 9-volt battery is needed

I bought these but returned them thinking it was just a faulty item , got a replacement and it too acted exactly like the first items I received. These will only hold a charge long enough to make you mad. A complete waste of money.

I don't need to worry about needing a 9V and finding I am out or they are all dead. This is an excellent design and great value.

About consistent with their 800 mah spec for a 3.7 volt single cell lithium battery, but not even close to the 9 watt-hour spec they advertised… Certainly good for many applications but below the 5 watt-hour or so capacity of a standard alkaline 9 volt battery.

Batter did not hold charge for long even without using. Maybe this was not a good one.

got these for my drop down gun safe, charged fully after delivery, failed instantly.