Boat Water Ski Tow Eye Hook Hitch -Small - Medium - 2 1/2" to 3" inch - Transom Mount - 316 Marine Stainless Steel Material: All 316 marine grade stainless steel - high polished finish. Maximum corrosion resistance and durability in the saltwater environment. Thread length: 2 9/16". Sizes: Small - 2 3/8" outside ring diameter. See additional specifications in product description below.