This is a Darice product and the package reads, "18in. chain with add-a-bead easy clasp-bright silver". The little photo on the package shows how the clasp pulls apart easily. "Simply pull apart clasp to add beads and charms".
Again, I say, how cool is that?!! This would be a great product to use with new beaders. There is nothing intimidating about adding beads to a chain and would probably rope some new, unsuspecting beadaholics right in!
I don't see a measurement for the diameter of the chain, but I just tried one of yesterday's swarovski cubes and the hole was just a little too small. So, here I go to dig around in some bead containers!! Have a good one!!