These heavy duty ship cleats are the same malleable iron hot dipped galvanized material as our galvanized cleats, but are much heavier duty, about 2x stronger than a standard galvanized cleat. The 12" Steel Ship Cleat uses 5/8" hex bolts (not included) to bolt in place. We don't include the bolts because attachment methods vary greatly which changes the length of the bolts you need. Browse our full selection of Hex Bolts today!