This is an Onyx 6S 30C 7000mAh LiPo Battery with an EC5 connector.

Specifications:
Battery Voltage: 22.2V
Capacity: 7000mAh
Connector Type: EC5
Height: 1.9" (48mm)
Length: 6.6" (168mm)
Maximum Continuous Discharge Current: 210A
Maximum Continuous Discharge Rate: 30C
Weight: 33.9oz (960g)
Width: 2.4" (60mm)