... / 12", 24", 36 b) Width: 300, 600mm / 12", 24" Armstrong ceiling: Dimensions: a) Length: 300, 600, 1200mm / 12", 24", 36 b ... ) Width: 300, 600mm / 12", 24"Armstrong ceiling:Following are mainspecification of our Mineral ceiling board:Width: 300mm,600mm. Length: 300mm,600mm,1200mm(British ...