All our murrine are made of Murano glass (coefficient 104) and can be used with glass sheet, rods and grits of the same coefficient. Please note: The dimensions are variable. in description you will find the minimum and maximum diameter that you will find Con the package. In the site https://vetrocolorato85396.blogofchange.com/27168393/una-chiave-semplice-per-vetro-colorato-unveiled