Use this under your frame for a solid firm foundation when on a level surface. Our base plate has a hole at 2.5 inches to accept most types of scaffolding. Can be used in conjunction with a caster jack which allows maximum versatility. You can order the caster jack for use with casters or take the caster out and use the base plate to form a level jack for a stationary application. ScaffoldMart base plates come galvanized and weigh 1.5 pounds each. For use with #6 (1.375" OD) tube size only.