21700 Batteries & Chargers
21700 battery size / type is the newest generation (2019) of cylindrical Li-ion rechargeable 3.7V cells.
21700 battery charger featuring specially designed charging bays ready to accept (approximately) 70mm long Li-ion cells.
The best 20700 Li-ion 3.7V batteries - also available, and 21700 backward compatible. 1mm smaller in diameter but very powerful.