#20 nickel-plated steel ball chain.
Large, heavy-duty ball chain necklace is created of nickel-plated steel. Toggle clasp.
Please see second image below for size comparison. 10mm chain is shown on the left. The larger chain shown on the right is 1/2" diameter #30 ball chain.
Measurements: #20 ball chain is 18" long. Each ball is approximately 3/8", or 10mm, in diameter. Approximately 84 grams.