The 18650 battery is a lithium-ion cell classified by its 18mm x 65mm size, which is slightly larger than a AA battery. They’re often used in flashlights, laptops, and high-drain devices due to their superior capacity and discharge rates. 18650s come in both flat and button top styles, and usually boast 300-500 charge cycles. Lithium batteries are a great option for today’s high-end electronics as these cells typically have higher capacities than their alkaline counterparts. Although rechargeable batteries tend to cost a little more than standard alkaline batteries up front, these costs have reigned in because you won’t need to replace rechargeable batteries nearly as often as alkaline cells. According to different conditions, Battery capacity can be divided into actual capacity, theoretical capacity, also called rated capacity.Battery capacity refers to the battery storage capacity.The unit is "mAh", 1Ah = 1000mAh, so there are some differences between rated capacity and actual capacity in Li-ion Battery.It is normal and reasonable.Rechargeable batteryRecharging/ Discharging protection circuit.Discharge rate.No memory effectLow reccuring operation cost.Short -circuit and over-current protection.Safe and environmental friendly.Keep in a dry and cool place.Sheef-life around 10 years.