Expansion Bolts are for heavyweight fixings in concrete, masonry or natural stone. Great for installing a safe into the wall or floor. Vertical and horizontal loads can be handled. When tightening the bolt the nut is pulled into the shell expanding it and wedging it outwards inside the anchor base. Yellow passivation coating making it more rust resistant. Expansion bolts are used for heavy duty fastening and fixing of steel or wood structures to masonry, concrete or bricks.