8 ft. to 13 ft. Aluminum Extension Plank. Rest this plank between 2 ladders or on ladder jacks to have a staging platform that can hold up to 275 lbs. Made of extruded aluminum bars 2 in. deep, with a platform consisting of extruded aluminum cross members riveted to the bars. The extension can be locked in a variety of increments and it opens and closes smoothly on molded plastic spacer guides. End flanges are made of heavy-duty aluminum crossbars that give the planking additional rigidity.