M-Glass Shaft Liner panels consist of a fire-resistant type X gypsum core that is encased in a moisture and mold resistant glass mat fabric. The panels feature a double beveled edge for ease of installation, with the ends being square-cut and finished smooth. M-Glass Shaft Liner panels are available: 1" thick x 2' wide, and in a variety of lengths. American Gypsum products contain no asbestos and no detectable levels of formaldehyde.