This unique locking differential has two operation modes. The first is an open differential mode for smooth street driving. The second mode is a full spool mode to provide you with the maximum available traction. This differential goes from open to lock with the flick of a switch. This differential includes a forged differential cover with an integral air cylinder for smooth and reliable operation and serviceability. All components are fully machined here in the U.S.A. Requires use of external air source not included.