This is the 7.4v. 4500 mAh 60C Ultimate Racing Lipo Battery Stick LW Pack with t-Dean connection. Capacity: 4500mAh Voltage: 7.4V (2S) Dimensions (mm): 138x47x24 Max. charge current: (5C) C-Rates: 60C Weight: 210g
2 of these can be used in the Ultimate Starter Box without any need for extra leads or soldering different connectors.