When the trail is on a sideways incline, usually very steep. Off-camber trails increase the likelihood of a rollover.
On Board Air (OBA)
A system consisting of some type of air compressor w/ or w/o accompanying air tank usually driven under engine power. Used for airing tires and/or running air tools.
A differential that usually comes stock on 4x4s. It directs power to the wheel with the least resistance to spinning. One-leggers and peg-leggers are slang terms for open differentials.