Sierra BS11030 Battery Switch w AFD - 12BOTHOFF Sierras BS11030 Battery Switch is a 4-function switch with Alternator Field Disconnect AFD that can support 2 battery inputs. This switch has an 1-2-BOTH-OFF function. The BS11020 features a unique ergonomic knob thats designed to be removable for an added level of safety and isolation. Additionally, this switch has a robust glass fiber reinforced nylon enclosure for added durability. Surface or panel mount options provide flexibility during instal