This is a quality, high grade, marine stainless steel (AISI 316) ISO G4 chain suitable for use in a windlass as anchor chain or other marine applications where high corrosion resistance is desired. Superb for anchor chain and general heavy duty work in a marine or chemically harsh environment. This chain will fit many standard windlasses. Please consult your windlass manufacturer model manual for the ideal specification for your windlass. The 3 important figures for smooth running or your windlass is the Diameter (DIA), Inside Length (IL) and Outside Width (OW). More details are in the spec table below. This chain is 13.1*40*45 (DIA*IL*OW). The measurements of this chain are listed in mm and as G4 is generally considered an Imperial chain, the Imperial spec of this chain is 1/2*1.57"*1.77".