This GOLISI O4 Charger is an economic and practical charger that converts high electricity voltage into suitable voltage for battery charging. Its non button design means it is easy to use and automatically distributes current to each cell. A military grade loading spring that has a 100k cycle life ensures it is long lasting and that it can charge a vast range of battery types. Features Military Grade Loading Spring: 100K Cycle Life Manufactured From High Quality ABS+ PC Fire Proof Materials Compatible Battery Types: 18650, 26650, 20700, 21700 AAA, AA & Others 32mm-70mm In Length Smart Temperature Regulation & Protection Built-In USB Output That Can Be Used As A Fast Charging Power Bank 2A Lightning Fast Charging Reverse Polarity Prevention