BD units, also called BD explorer droids, were a model of explorer droid.
BD units were companion droids designed to assist with operations in remote and dangerous locations across the galaxy; programmed to be the ideal assistant to researchers or explorers operating alone in the field, they were designed to traverse all types of terrain. As a result of their manufacturer collapsing, BD units were a relatively rare sight in the galaxy. A type of similar looking and similarly named droid, the BDX droid, also existed but was much larger in scale.
