The OOM-series battle droid was the predecessor of the B1 battle droid. While physically identical to the latter, the OOM-series possessed more advanced and independent programming. They were already a common sight in the galaxy before the Invasion of Naboo, serving as security and crew for the Trade Defense Force. They later served in the Clone Wars alongside their more common but simpler B1 descendants. They were deployed during the Battle of Tirahnn. OOMs could be programmed for a number of functions, each with a matching color painted on the droid's body: