It's a 2200mah and I get about 10 hours of use per charge. I charge it with a Hobbico Quick Field Charger MkII. The cells I used are flat and measure about 2 5/8" long, 2 1/8" wide, and 3/16" thick. That's each cell. I know it fits the R-1 and 3pk just take out the battery tray and add some foam to take up the dead space. You'll have to take a little material off the radio under where the tray sits to get the battery to sit low enough to clear the battery door.