This is one of the finest Show Chains on the market...Solid Brass with 22k gold plating and a protective clear coating ....and will not rust....This FINE curb-link chain is 1.4 mm thick... (a little under 1/8"). The seamless end-rings are 3/8" in diameter. Collar size, 20", does not include the outside ring measurements....... The beautiful chain has the look and feel of fine jewelry.