This is the Series Wire Harness with 6.5mm Connectors from Castle Creations. Features: Connects two battery packs in series combining the voltage output For use with 1/8 and 1/5 scale ESCs 10AWG wire INCLUDES Series Wire Harness with 6.5mm Connectors Specs: Connector to Connector Wire Length: 5" (127mm) Overall Length: 6.75" (171mm) Weight: 2.01oz (57g) Note:Both battery packs used with the harness must be identically prepared, fully charged and properly balanced. Both must be the same brand, same C-rating, same capacity and level of charge. Failure to observe this warning will result in damage to batteries or fire.