This is the 2S 2ft Charge Lead Cable with 4mm & 5mm Bullet Connectors from Avid RC.

Designed to be color coordinated (e.g. Red uses all red wires and sheath) for charging 2S battery packs through 12ga wire. Includes gold-plated 4mm to 5mm bullets on the battery end to cover all battery types and a 4mm bullet on the charging end. Comes with the popular XH 3pin balance plug, which most trim one of the plastic alignment rails with an x-acto to plug right into the charger instead of the balance port. Or you can use the included XH 7pin if you don't want to brave that. Balance leads are 2.5" (63.5mm) longer than the charge leads so they can easily be plugged into any charger design.