The SPD-R4 spider droid was a model of service droid/maintenance droid commonly used in Imperial installations such as the Death Star I and Mount Tantiss; aboard automated ships such as the Another Chance; and by civilians.
The model was spider-like, with a spherical metal body and eight multi-jointed legs covered with cleanser application nozzles, grippers, and cutting blades. Its bendable appendages allowed it to easily navigate power cores and engine blocks aboard the Death Star I, carrying out repair and maintenance in places inaccessible to Humans. The droid also possessed welding/defensive blasters. In addition to maintenance and repair, the droids could serve as pest exterminators, targeting exogorths, mynocks, and vervikks.