KingPin 7" x 7" Stainless Steel Square Base (Threaded)KingPin 7" L x 7" W Satin Stainless Steel Threaded Square Base with Nylon Bushing for 1-3/4" D Post (1630001) by Springfield Marine. Springfield Marine knows that comfort is important in marine seating. Whether behind the wheel for long passages in rough water; dropping a line in a quiet creek; or anywhere in between, Springfield Marine offers a wide range of configurations and options.Features:. 7" x 7" stainless steel base, with nylon bushing and satin finish. 4" cup depth below the deck. Mount requires a 2-1/2" hole in the deck. Built to provide secure, hassle-free boat seat mounting. Specifications:. Post Diameter: 1-3/4". Length: 7". Width: 7". Finish: Satin. Material: Stainless Steel