![Amazon.com: XTAR X4 Extended Version Protected 21700 20700 Battery Charger LCD Display AC Input Port 18650 Charger 2A Fast Charger with Mirco USB Output for Rechargeable 3.6V 3.7V Li-ion 1.2V Ni-MH Ni-CD Amazon.com: XTAR X4 Extended Version Protected 21700 20700 Battery Charger LCD Display AC Input Port 18650 Charger 2A Fast Charger with Mirco USB Output for Rechargeable 3.6V 3.7V Li-ion 1.2V Ni-MH Ni-CD](https://m.media-amazon.com/images/S/aplus-media-library-service-media/44952a6c-4eb2-4a6a-bd38-dfcaaf3caa4d.__CR0,0,970,600_PT0_SX970_V1___.jpg)
Amazon.com: XTAR X4 Extended Version Protected 21700 20700 Battery Charger LCD Display AC Input Port 18650 Charger 2A Fast Charger with Mirco USB Output for Rechargeable 3.6V 3.7V Li-ion 1.2V Ni-MH Ni-CD
21700 vs 18650 Lithium-ion Battery Cells, Packs, and Technology | 21700, 18650, 20700 and others simply refer to the physical size of the lithium-ion #battery cell. For 18650, it's an 18 mm
![18650 Battery Adapter 20700 21700 | Diy Power Bank 21700 Battery Case - Battery Storage Boxes - Aliexpress 18650 Battery Adapter 20700 21700 | Diy Power Bank 21700 Battery Case - Battery Storage Boxes - Aliexpress](https://ae01.alicdn.com/kf/S0b6c822d92d442a08e07c4af6f2c987da/18650-18700-20700-21700-Battery-Charger-Adapter-Battery-Pack-DIY-Power-Bank-for-iPhone-Power-Bank.jpg)