A C-rate in batteries is about how much a battery is discharged relative to its capacity. In this video Rock Rose compares Lipoly batteries for airsoft use by their C-rates... "There are too many people who don't know about C rate and battery output, so I've included an explanation. Very few even shop clerks understand it correctly, and we often see people explaining lies to customers. Get the right knowledge and choose a battery without being fooled by the clerk. By the way, nickel-metal hydride batteries are roughly equivalent to 15C, and unlike lipo batteries, the C rate cannot be changed for each product, so the notation tends to be omitted."