This is a quality, high grade, galvanized chain specifically cut for anchor chain. The link size is 1/4" or 6mm equivalent. The chain includes oversized chain links on both ends for easy attachment. Included are two oversized galvanized anchor shackles. Each US style galvanized shackle is 5/16" (6mm) with an oversized pin of 3/8". The total length of chain is 4' measured before the shackles are added. The chain link is in the US specification style of 1/4" (for the chain link size) and the shackles are made in the imperial style of 5/16". The metric equivalent is generally considered to be 6mm for the chain link size and 8mm for the shackles.