Here are some screen shots of what the DR Pulley sliders do differently from rollers. This is actually a very nifty invention and has been patented. Good for them. . . . . . . . . . The only draw back seems to be the possibility of the low ratio going below the design threshold and allowing the belt to go slack on some bikes which causes a shudder on take off until the weights swing out to take up the slack. Some people have had to add a shim to stop the travel of the variator. . .