One of the largest luxury bus builders in the US called LM76 when they wanted to install large LCD screenson their buses. The LCD screens weigh 80 pounds and slides out 6 feet. One of the design parameters was weight.The SG Speed Demon is a lightweight extruded rail with twin steel shafts hosting gothic arch steel rollers. LM76'sMike Quinn recommended a 5 roller SG block, " We needed a system that would guarantee smooth, easy movementregardless of where the operator pulled the screen from. Secondly, we had to support the LCD screen when it was fully extended or unsupported - full cantilevered load."