This is a 2S balance/charge adapter from ProTek R/C. This adapter is designed for 2S Li-Poly hard packs that use two 4mm bullet connectors for the main power connection, and a 2mm bullet connector for the balance connector. This adapter is approximately 16" long tip to tip, has bullet connectors on the battery end, a female ultra-plug to attach to your charge lead, and an XH style balance connector to connect to your balancer on the other end.