What do you expect from batteries? These UltraFire TR 18650 2400mAh 3.7V Lithium Rechargeable Batteries will allow you to get incredible runtime.Protection circuits are attached to these lithium rechargeable batteries to ensure that you do not overcharge or over discharge them. The UltraFire rechargeable batteries feature a button top, which make it particularly compatible with many flashlight applications. And these 18650 rechargeable batteries hold a charge longer than traditional batteries. More important, the lithium rechargeable batteries are of high capacity and low consumption. With these lithium rechargeable batteries, you always have fresh batteries for your electronics.Rechargeable lithium batteries are rapidly becoming a very economical way to lower the operating costs of lithium-powered flashlights. Practical and reliable, try these batteries!