So you just bought your brand new Olight M21-X Tactical flashlight, but you also need some batteries to toss in there. Look no further, Olight still has you covered with their 18650 battery, which is a rechargeable lithium-ion battery. These 18650 batteries provide high performance and can be recharged up to 500 times, saving you money in the long run. Each battery comes equipped with a built-in circuit protecting board and triple over-heat protection, so you don't have to worry about your M21-X cutting short on you. Olight has thrown in a higher capacity and lowered the weight opposed to other 18650 batteries. You don't have to worry about over-discharging the battery as you are protected there as well.