Universal Air Locker Dana 30 27-Spline 3.54 & Down (ARBRD101)Description This pneumatically operated air locker provides instant, switch activated lockup at any speed for maximum traction in the toughest terrain. When activated it ties both wheels directly to the ring gear; when unlocked it operates like a conventional open differential for safe, controlled driving. Features Pneumatic switch activated locking Instant lock at any speed Operates as an open differential when unlocked Super strong design for