4 x 3.7V 18650 Li-ion rechargeable batteriesMaterial: li-ion, Lithium ion battery model: 18650 Capacity: 4200 mah Resistance: 20 or less milliohm weight: 20g Ruler high form to: diameter of 18 * 35 (mm) Charging time: 1000 battery voltage: standard voltage 3.6 / 3.7v, voltage up to 4.2v after charge, voltage up to 2.75v after discharge 【 Product Features 】 1. Features: high safety performance, no explosion or combustion; Non-toxic, non-polluting; Consistency is good, long life, more than 1000 cycles; High temperature resistance, overcharge resistance 2. Safety: The battery has excellent safety, no fire or explosion,