Common Sense RC Lectron Pro 6.6V 3200mAh LiFe Receiver Battery with EC3 Connecto

6.6V indicates you won't require a regulator!

This 6.6V (2-cell) 32000mAh 5C LiFe (lithium iron phosphate, LiFePO4) receiver battery offers a terrific mix of performance and benefit. Our LiFe batteries have some special benefits over other battery alternatives that make them perfect for use in radio systems:

Voltage stays above 5V throughout your whole run, so you get more consistent servo speed and torque than with NiMH batteries
Somewhat lower voltage than Lipos indicates you can safely link 6.6V (2-cell) LiFe batteries to your receiver without requiring a voltage regulator
3200mAh capability is perfect for larger aircraft and vehicles with numerous power-hungry servos
Separate EC3 port and 14 awg leads for strong applications

Specs
Adapter: JR (Universal) Servo Adapter

Measurements:
Length: 86mm (3.39 in.)
Width: 49mm (1.93 in.)
Height: 19mm (0.75 in.)
Weight: 162g (5.71 oz)