These are glass rods from a "tonbo-dama (glass bead) making experience" I had about 10 years ago. I've kept them as they are since then, and I'm considering getting rid of them. 5mm thick, 15 rods (+ 1 thin rod) *I am unable to answer questions about the material as I purchased them a long time ago. They will be sent in a box packed with recycled materials. Please consider the above before making a purchase.