This is a heavy duty 2S hard case lithium polymer battery charge/balance adapter lead from SpeedTek RC. This 13" long charge lead allows you to plug a 2S battery with 5mm female bullet connectors directly to your charger, eliminating the need for a balance board!
 
This adapter lead features 4mm banana plugs on the charger end, and 5mm banana plugs on the battery end, connected with 12awg wire. The balance wires include a 2mm banana plug on the battery end, with a 7-pin XH plug connected with 22awg wire for balancing that is plugged directly into the 6S balance port in the charger. This charge lead is specifically designed to connect a SpeedTek RC 2S LiPo hard pack with 4mm connectors to SpeedTek RC chargers, but will also work with any charger that uses 4mm bullet connectors for output, and has a 7-pin (6S) XH balance port.