8 Slots 18650 Battery Charger XTAR VC8 Charger USB C 3A Fast Charger 21700 Battery Charger with LCD Display for 3.6V 3.7V Li-ion 10440 18700 26650 1.2V Ni-MH AA AAA C Full Set with QC3.0 Wall Charger

This is what I use. https://www.amazon.com/Battery-Charger-XTAR-Display-Li-ion/dp/B0836VHG67?pd_rd_w=q5Xhm&content-id=amzn1.sym.25d4e176-acb1-4d0b-bb81-b4cc6b733b36&pf_rd_p=25d4e176-acb1-4d0b-bb81-b4cc6b733b36&pf_rd_r=W54FKYKM2RS2MFBV7PN9&pd_rd_wg=a9b8V&pd_rd_r=24aab186-5938-4f5a-b289-8376bbab7015&pd_rd_i=B0836VHG67&psc=1&ref_=pd_basp_d_rpt_ba_s_1_t If you are using a battery charger, you can use any 21700 that fits your Olight.