This is a quality, high grade, marine stainless steel (AISI 316) DIN766 chain suitable for use in a windlass as anchor chain or other marine applications where high corrosion resistance is desired. This listing is for 20' of windlass chain before the shackles are added. Two quality shackles are included with the chain. 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 8*24*27.5 (DIA*IL*OW). As DIN766 is a metric specification we list the specs in mm, the imperial equivalent of this chain is 5/16"*0.95"*1.08". The link size is 8mm or 5/16" imperial equivalent. Every 3 feet links are hallmarked and stamped with 316.