CONTINUOUS SOUND ABSORBING PERFORATIONS FOR A MONOLITHIC APPEARANCE Product Details: Perforation: 20mm / 33mm o.c. Panel Thickness: 1/2″, 12.5mm Non-Woven Fabric Backing: Charcoal Gray Finish: Unfinished paper face Open Rate: 28.69% NRC: Up to .85 Board Sizes: 1188 mm x 1980 mm 1188 mm x 2376 mm 1188 mm x 2673 mm Product Data Sheet: Sonus Round 20/33