The BS4 is bebob's portable Quad B-Mount Battery Charger, built to keep a set of B-mount batteries topped up through a long shooting day. It charges up to four B-mount batteries at once, each fed at 16.8VDC and 2.5A through a 4-pin XLR output, so a full set of batteries can go from set back onto charge together rather than one at a time. Its 4-channel design suits a larger crew rotating several B-mount packs across multiple cameras or lights.