See the pink, thats a tube, the green is a non-streching material. you slide this inside the tire when you putting it on, put in a second valve stem (for the tube). Mount and inflate your tire, then blow up the tube, the green keeps the tube from expanding holding tube in and making buldge out holding both beads tight on the rim. Internal (pnematic (sp?)) beadlock. kert Bolden ran/runs them on his K5/jimmy, looks cool with the two valve stems, I like them because I'm lazy and dont want to mess with 100 some odd little bolts /forums/images/graemlins/doah.gif