Gr 30 - Proof Coil: A general purpose chain of normal commercial quality. Constructed from low carbon steel. Proof coil chain doesn't have a uniform pitch and does not work with windlasses. It is hallmarked approximately every foot with the manufacturer's symbol and grade marking: 3, 30 or 300

BBB Anchor/Windlass Chain: A short link chain of normal commercial quality. Constructed from low carbon steel. It has a uniform pitch short link and works well with gypsies. It used to be the standard for windlasses but it has largely been replaced by G4 Chain. It is hallmarked approximately every foot with the manufacturer's symbol and grade marking: 3B

Gr 40 -High Test: This is the standard for most windlasses today. It is almost identical to Gr 43 chain except it has a smaller chain links that are to ISO standards. It has twice the working load of BBB chain which allows a smaller chain size to be used. It is hallmarked approximately every foot with the manufacturer's symbol and grade marking: G4

Gr 43 -High Test: Made from high carbon steel, it has a strength, size for size, approximately twice that of proof coil chain/BBB chain. It is hallmarked approximately every foot with the manufacturer's symbol and grade marking: 4, 40, 43 or 400.

Gr 70- Transport: This chain is commonly called G7 or transport chain. It has a very high strength-to-weight ratio and it has about 25% more strength than high test chains. It works with very few windlasses however. It is hallmarked approximately every foot with the manufacturer's symbol and grade marking: 7, 70, 700.