SLU is a circular straight silencer
Nominal insulation thicknesses is 50mm.
Attenuation material is mineral wool. The SLU's are made of strong outer spiral seemed tube and an inner tube made of perforated sheet steel with small openings to be able to withstand mechanical cleaning and at the same time not interfere with the insertion loss. The space between them is filled with mineral wool and a nonwoven cloth is inserted between inner tube and the attenuation material, to prevent fibres from the insulation getting into the duct system. Silencer can be cleaned by rotating nylon brushes, vacuum cleaner or damp cloth.

Tested according to ISO 7235 standard.