The Turnigy 2650mAh Transmitter pack fits snuggly into any Futaba or Jr radio which uses a 4x4 AA cell battery configuration (see image). It includes discharge plugs for both JR, Spektrum plus other radios. It's built with a low C-rate Long Life LiCo Formular which isn't like a standard LiPo. It retains voltage for months on end without need for a storage charge so you can store your radio and fly once a month and not have to worry about discharging or recharging your pack.
With a capacity of 2650mAh this lipoly replacement for your old NiCD or NiMH will last four to five times longer. Probably the best advantage with a lipoly transmitter battery is that it will give a true voltage reading from start to finish which means you can say goodbye to the days where you thought your Transmitter was fully charged at home, only to find the voltage drop off rapidly when at the field.
The battery came with the output polarity reversed. Damaged my Transmitter and now HobbyKing does not want to stand behind their product. If I could give this battery negative stars I would, along with their lack of support for a manufacturing defect. Hobby King is off my list of places to purchase.