He is talking about pack config. MS packs are 2S2P (2 series, 2 parallel), so 1SNP means 1 in series (hence the need to double the 3.7V) with X number of cells in parallel: 3, 4, 5 whatever.

Probably cheaper/easier to design the light to work off 3.6/7V. All of EL34s light work that way, as does the DX Eastward apparently.