Futaba charging adapter: Futaba J female connector at one end, and Banana Plugs (aka 4mm bullet connectors) at the other end. Enables smart-charging of Futaba receiver and transmitter battery packs. 22AWG wire, 18" long. You can also plug JR, HiTEC, SPEkTRUM, and Airtronics Z male battery connectors into this Futaba female.