4x4 Posi-Lok PSL400 Axle Disconnect 4x4 Posi-Lok reduces front differential wear and right axle breakage. 4x4 Posi-Lok provides 2-wheel drive low range, giving the vehicle 4-LO torque at the rear axle with bind free steering only available in 2-HI. This feature is not available with factory systems and is beneficial when maneuvering trailers 4x4 Posi-Lok will not disengage when ignition is turned off or the differential is submerged 4x4 Posi-Lok is compatible with manual or electric transfer cases and installation can be completed in one to two hours with basic hand tools. No internal differential work is required.