This is the Spektrum 6.0V 2700mAh NiMH Receiver Pack Battery.
Specifically designed to be the ideal battery pack for use with the Spektrum AR9100 receiver and built to fit easily into nearly any fuselage, this 6.0V 5-cell receiver pack from Spektrum offers an installed EC3 lead for quick and easy usage, high capacity Sanyo cells, and a 6-inch JR charge lead for added convenience.
Connector Type: EC3 with JR type charge lead
Cell Size: Sanyo AA
Wire Gauge: 16AWG
Number of Cells: 5
Weight: 7.1 oz / 200g
Length: 2.8 in (71mm)
Width: 2.0 in (54mm)
Height: 0.6 in (15.3mm)
Application: Designed for use with Spektrum's AR9100 and AR7100 receivers