The SliderPLUS Large from edelkrone is a slider that uses a unique tracking mechanism that allows the rails of the slider to move with the camera when mounted on a tripod. This gives the slider 31.5" of sliding range in a unit that is only 21.1" long. Its compact sizes makes it ideal for travel, as it takes of up less room in your camera bag than other sliders with a similar sliding range. The slider supports loads up to 8.8 pounds.
The tracking system works by having two thin bands that are connected to each side of the mounting plate and base plate. When placed on a flat surface, the base plate travels in the opposite direction of the mounting plate. This will yield results of traditional slider. To take advantage of the design, the SliderPLUS needs to be mounted to a tripod. When mounted on a tripod, the movement of the base plate is restricted, causing the rails to move through the base plate in the same direction as the mounting plate.
With traditional sliders, you're often limited to the amount of dolly in/out you can do, because the slider itself usually will end up in the shot eventually. With the SliderPLUS, the rails are also retracting backwards with the camera, allowing for longer dolly in/out shots. A lock mechanism can be engaged to keep the slider from moving if the tripod becomes unlevel.
The slider provides a 3/8"-16 threaded hole at the bottom of the base plate for attaching to tripods, and comes with interchangeable 1/4"-20 and 3/8"-16 screws for mounting a camera or flat base tripod head to the mounting plate.