A good quality 22650 flat top battery. The button top version of the battery can be foundhere.
18650 Battery Charger with 4 Pack Ni-MH 3.7V 3500mAh Flat Top Rechargeable Battery, 4 Bay LCD Display Smart Universal USB Dual Battery Chargers for 18650 18500 21700 26650 14500 16340 Batteries, Boxed
2pcs LiitoKala 26650 Lii-50A Li-Ion Flat Top Rechargeable Battery - 3.7V
Vapcell 20700 Li-Ion 30A Flat Top Rechargeable Battery - 3.7V 3000mAh
LiitoKala 18500 Lii-14A Li-Ion Flat Top Rechargeable Battery - 3.7V 1400mAh
14500 LiFePO4 3.2V 600mAh Flat top rechargeable battery. PKCELL.
2-8X 26650 Batteries 3.7V Rechargeable Battery Flat Top, 4Slot USB Charger
