Troges pipe sound attenuators consist of a lengthwise-seam outer tube of galvanised steel and a lengthwise-seam inner tube of galvanised perforated steel. The mineral fibre damping in between, with a thickness of 50 mm or 100 mm, is protected by glass fibre on the flow side against abrasion with air velocity of up to 20 m/s. The end caps are suitable for connecting to a pipe.