The 8'-13' Aluminum Extension Plank is ideal for use on step ladders, telescoping multi-ladders, extension trestle ladders and extension and single straight ladders equipped with ladder jacks. Positive stops on the plank prevent overextending. Molded thermo-plastic spacer guides allow for easy open/close action. Made of 2-inch deep box section extrusions. Heavy end flange/handles for rigidity and ease of operation. Outer flange is open for ladder jack clamps. The extruded cross members are riveted with solid aluminum rivets. Locking mechanism sets the plank in 12-inch increments. 250 pound load capacity.