Folding cleats for docks are made of grade 316 stainless steel, also as known marine grade stainless because of the very high chromium content to resist rust. Dock cleat use machine screws that go all the way through the deck and are fastened with nuts and washers on the bottom side. It is the satisfactory way to mount something that is so critical to retaining your boat at the dock. The center mounting screw really adds dock cleats steadfastness. Ideal for decks where you don't want to risk snagging things with a standard style cleat, because these boat cleats fold and present a smooth and low profile. Boat dock cleats flip up are ideal for decks where you don't want to risk snagging things with a standard style cleat. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1cm.