This is the Onyx 3S 11.1V 740mAh 20C LiPo battery with XT30 connector.
Voltage Rating: 11.1V
Rated Capacity: 740mAh
Maximum Charge Rate: 2.2A/4C
Discharge Rate: 20C
Burst Rate: 40C, 29.6A
Dimensions, L, W, H: 2.6 x 0.90 x 0.75" (66 x 23 x 19mm)
Weight: 2.1oz (60g)
Discharge Lead Wire Size: 16AWG
Discharge Lead Length: 3" (76mm) not including connector
Discharge Connector: XT30
Balancing Connector: JST-XH
Watt Hours: 8.2
Note: ALWAYS use a LiPo-approved Charger and Cell Balancer, charge in a fireproof location, set charger’s output volts to match battery volts and keep out of reach of children. Never charge over 4.2V per cell, charge at currents greater than 4C, trickle charge, allow to discharge below 2.5V per cell, disassemble or modify pack wiring in any way or puncture cells, or place on combustible materials or leave unattended during charging. All weights include wire leads and plugs, weights are +/- 1g, and measurements +/- 1mm.
Features: Ultrasonically welded cell tabs and balancing wires