A pair of good quality, LiitoKala 18500 flat top batteries.
2pcs LiitoKala 26650 Lii-50A Li-Ion Flat Top Rechargeable Battery - 3.7V
LiitoKala S2 Smart Battery Charger Ni-MH Li-ion 3.2V 14500 18350 18500 20700 UK
Liitokala 3.7V 18500A 18500 1850 Lithium Rechargeable Cell (1600mAh) - UK Stock!
2pcs Protected LiitoKala 26650 Lii-51S Li-Ion Flat Top Battery - 3.7V
Universal Li-ion Battery Charger - Dual Slot Smart Charger for 18500 18450 18500
18500 Rechargeable Battery, JESSPOW IMR 18500 Rechargeable Battery 1600mAh 3.7V [ for Flashlight, Solar Garden Light ] with Button Top (4 Pack)