RC hobbyists, this adapter cable lets you run two of your LiPo batteries in SERIES. That means you combine their voltage while keeping the same capacity (mAh). For example, two 3S batteries in series become a 6S pack. This is super useful for increasing your model's power/speed without changing the batteries themselves. The cable has one female Deans (T-Plug) connector on one end and TWO male EC5 connectors on the other end. It's made with thick 12AWG wire and is about 10cm (4 inches) long. CRITICAL WARNING: You MUST only use this with two batteries that have the EXACT SAME capacity (mAh) and similar charge levels. Using mismatched batteries can be dangerous. Also, remember this is for series connection (voltage adds), NOT parallel (capacity adds). Always double-check your connections and understand your electronics before use. A handy, well-built adapter for experienced users looking to get more voltage out of their existing EC5 battery packs for compatible ESCs and chargers.