Great for checking packs before use and after charges or before storing. * Shows at a glance the remaining capacity in your battery pack, cell balance, and other information you need to get the best performance and reliability from your batteries * Works wth most battery types on the market. Thunder Power packs require an optional adapter plug (purchased separately) * Works with Lithium Pack Sizes 2S-7S, NiMH and NiCd 4-7 cells.