Clasp: 1/2" (13mm) x 5/16" (8mm)
Jump ring: 18" (3mm) ID, 18 gauge
If you need a soldered ring to connect to your clasp then check out this pack of 10!
This lobster clasp is used in Colin Mahler's Byzantine Sunburst Chain class. The clasp has an open jump ring to attach it to your project.
Great quality for the price!