This is an ordinary grade 40 lightweight chain, widely used for anchoring boats or used as a buoy hook, for mooring and as a port beacon. It is not usually calibrated and comes in black or gloss. Boaters often request the galvanised lightweight chain as it has better resistance against corrosion from the sea water. The most common tread for the lightweight chain is 3.5.
It is also referred to as an anchoring chain.