Elevate semi-trailers to loading docks for maximum serviceability during loading and unloading operations. Manufactured from heavy-duty aluminum tread plate for positive traction. Welded all aluminum construction. 30,000 lbs. capacity per pair (Sold Each). Wheel Risers are designed to raise the trailer for loading and unloading to facilitate compliance with OSHA/ANSI B56.1 part 3 sec 7 requirements for a maximum grade of ascending or descending loaded fork trucks.