MHD—or Max Heavy Duty—is supplied as a kit of parts with two basic elements—bearing blocks and tracks. The system comes with a left and right block assembly. The bearing blocks run on a pair of 100mm by 40mm flat tracks. Tracks are hardened and fully ground on all surfaces, and are available in single lengths of 1.4m. The tracks can be butted together to provide a system of unlimited length, says the vendor.