•For sound attenuation in ventilation ducts and ventilated areas•Aerodynamically shaped sound attenuation splitter reduces drag by 30% (energy savings)•Sound attenuation splitters are made of flame retardant material, absorption material•Splitters are constructed in three standard thicknesses: d = 100 mm, d = 200 mm and d = 300 mm•Rectangular sound attenuators are available in five standard cross-section dimensions: d/s = 100/50; 100/100; 200/100; 200/200 and 300/100•Attenuator casing is made of galvanised steel, fitted with flanges meeting criteria given in the table on page 3•Attenuators heavier than 300 kg are supplied in two or more sections, each single section lighter than 300 kg