Use with two packs. Runs on MAIN pack till it drops out, then switches
to BACK-UP pack.
Works with standard 4 cell, 5 cell or GEL-CELL packs.
Battery packs can be different capacity like a 1200 and a 600.
Dimentions: 1.5 x 1.5
x .75 - weight .8 ounce.