POOVER 4-Pack 9v Batteries Rechargeable 700mAh Li-ion with 9v Battery Connectors for Guitar Multi-Meter

Compared to the 200mAh batteries that cost more, it's a no brainers. More than three times the capacity for less and rechargeable. (A batteries capacity is measured in Amp Hours or Milliamp hours. 700 mAh is .7Ah (Amp hours)). This means it will produce 700 millions of current at 9 volts continuously forv1 hour (you're not going to tap that capacity in normal use). So, 9 volts times .7 amps is 6.3 continuous watts for 1 hour. Or 12.6 watts for a half hour. Or 1 watt for 6 1/2 hours. You get the idea.

One of the four batteries arrived damaged. The others seem to be working well. They were packaged well so it was probably not damaged in shipment. One of the terminals is loose and the upper part of the plastic looks melted. Battery is completely dead...