Locking differentials allow both wheels to travel at the same rate of speed, so even if traction is lost for one wheel, both wheels will still keep spinning regardless of the amount of resistance. They can be added to the front or rear axle, or even both axles if you’re doing some serious wheeling. For instance , if you’re crawling up a trail and one of your wheels ends up off the ground an open differential is going to send all power to the wheel with the least resistance. Automatic locking differentials (Detroit Locker Aussie Locker, Yukon Grizzly Locker) are exactly what they sound like, differentials that lock automatically without requiring the driver to do anything. Some automatic locking differentials, or full-time lockers, only unlock based on the driving conditions, meaning that all other times the diffs are locked. While the driver has little to no control over automatic locking diffs, selectable lockers grant the freedom to switch between a locked and open differential freely. There are electric lockers (Eaton E-Lockers) and air actuated (ARB and Yukon Zip Locker) selectable lockers to choose from.