Rechargeable batteries are the friendlier choice for the environment but all too often this type of batteries fails to live up to expectations. Many rechargeable batteries can overload short circuiting and becoming useless. These UltraFire 18650 3.7V "3600mAh" Batteries solve that problem with their protection circuit board (PCB). Placed on the negative electrode of the batteries the PCB guards against overcharging helping the batteries to last for as long as possible. For this great low price you get a pair of 3.7-volt batteries that can be used in a wide variety of lights and other electronic devices. You can charge the batteries in any standard charger. Normal 0 7.8 ? 0 2 false false false EN-US ZH-CN X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:????; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; line-height:115%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri""sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} The UltraFire 18650 rechargeable Lithium battery is equipped with a protection circuit board (PCB) on the negative pole. The PCB can protect the battery from overcharge over-discharging overload and short circuit which can make the battery safer and longer lifespan. The battery is environment friendly and perfect for super bright flash and other devices. - Lithium Ion 18650 cylindrical rechargeable batteries - Lighting or other device needing 3.7V power - Product print '3600mAh' the exact capacity is 1000mAh - 2-Battery included