The OG-9 homing spider droid, sometimes referred to as the spider walker or the Separatist spider droid, was a droid walker manufactured for anti-vehicular combat by the Commerce Guild before and during the First War.
Like the many types of walkers, it was effective against both ground-based and airborne targets and was designed to transport a large and devastating weapon throughout the battlefield. The homing spider droid's round, armored body contained a volatile reactor. If the core was breached, the reactor violently exploded.
The homing spider could cover wide areas of the battlefield with its four all-terrain legs. Because of its great height and extendable hydraulics, the walker could position its homing laser above its fellow droids at enemy targets or move to higher ground to blast at air vehicles. However, the legs were vulnerable to damage, and if just one hydraulic leg was disabled, the entire vehicle would crash to the ground. This was fairly easy to do because it was a slow vehicle. Despite its weaknesses, the homing spider could walk along the bottom of seabeds, fully submerged in water, as well as scale steep cliffs.