This is the Hobbico LiFe 6.6V 1100mAh 10C Receiver Battery Pack.

LiFe (lithium iron phosphate LiFePO4) offers a lightweight, high
energy density battery with more power than NiCd and NiMH receiver
batteries provide
Nominal voltage rating of only 6.6V typically does not require a
regulator to power receiver and servos
Three discharge leads;
Two with Universal Receiver Plugs with 22AWG 5.1" (130mm) long wire
these are for models with dual power switches, regulators with
redundant inputs, redundant radio systems, or for applications
that draw more current than a single plug can safely deliver
One Discharge Lead with Deans Ultra Female Plug 14AWG 5.1" (130mm)
for voltage regulators, power distribution boxes and applications
drawing more than 10 amps

Hobbico LiFe 6.6V 1100mAh 10C Receiver Battery Pack with one Charge
Lead and three Discharge Leads

Charger such as the Hobbico LiFeSource AC/DC Balancing Charger
(HCAM6375)
(only use chargers that specifically say they are compatible with
LiFe cells)

Capacity: 1100mAh
Number of Cells in Series: 2
Rated Voltage: 6.6V
Continuous Discharge Rate: 10C (11 amps)
Maximum Recommended Charge Current: 2C (2.2 amps)
Charge Lead: 24 AWG, 1.2" (30mm) long wire w/ElectriFly Balance
Connector
Dimensions: 1.4 x 0.59 x 2.5" (35 x 15 x 65mm)
Weight: 78g (2.7oz) including all plugs and wires