Product description Wellyoung acoustic perforated gypsum board is designed on the basis of helholtz resonance theorem, After perforated, the holes, board and the wall make up of many resonant cavities, when air molecules pass the holes, the resonant cavities will consume large quantities of sound energy. It is widely used in auditorium, office, cinema, hospital, school and so on. Based board Knauf gypsum board or common gypsum board Thickness 12mm Size 1200*2400 Square hole 3/8.33, 5/15, 8/20, 10/20, 12/25mm Round hole 6/18.18, 6/20, 6/25, 8/18, 8/17, 8/20, 8/25, 10/20, 10/25, 12/25, 15/30mm Cross hole 6/10/20, 6/10/25, 8/12/25, 12/20/30mm Irregular hole 8/15/20 Oblong hole 4-14mm