Mugen Seiki 1500mAh Power Pack
New from Mugen, for use in their MBX-6, MRX-4 as well as their MTX4-R, is this new 1500mAh receiver battery pack. Claiming to have 50% more capacity than previous versions, this 6V nickel-metal hydride battery is protected by black shrink sleeving and is available with either a Sanwa/Airtronics or a Futaba type plug.
Source: Mugen [mugenseiki.com]