Whoa wait a min. here.
All glass in not created equal. What is used in those pics is food grade tempered glass swizzle sticks.
Those are made to mix drinks in bars and can take being whacked around a bit. They are made to be chip and crack resistant, don't want people getting glass chips in their mixed drinks.
I won't say it's unbreakalbe but it takes quit a bit of pressure to do so. A dang bit more so than I'd want to use in sounding play. Yes I've broken a couple just to see what it takes.
I shop around and don't go for the cheap stuff, bargins yes cheap no.
I also inspect them before each use, real simple hold up to a light and look for cracks or chips; then my fingers over the surface.
Around my cock are metal rings can be found in most hardware or farm supply stores where they sell rope and chains.