They allow you to disconnect the wheels from the axle shafts, differential and front driveshaft. They are great for higher speed or on road driving because they save all that stuff from spinning. When you unlock the hubs you'll have no 4wd at all - they disconnect the wheels from the axle shafts. When you want to use 4wd or have it on demand you would get out and manually lock the hubs (takes 2 seconds). I have a set of Mile Marker hubs in the box that I'll install over the holidays on my Roxor. Hope this helps.