The Turnigy 2650mAh Transmitter pack fits snuggly into most Futaba or Jr radios which use 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.

Spec.
Capacity: 2650mAh
Voltage: 11.1v 
Constant discharge: 1C
Burst discharge: N/A
Weight: 157g
Size: 98x30x27mm
Plugs: Futaba, JR/Spektrum
Balance Plug: JST-XH