The sound absorber has a perforated film (1) made from metal, where the perforated film is provided with a perforation. The film has holes (3) of the perforation with a hole diameter (d) between 0.5 millimeter and 1 millimeter. The hole diameter of the per...

The turbo supercharger (10) has turbine housing (11) which is provided thermal insulation layer (17) formed on the housing inner wall (12). The insulation layer comprises a top layer (19) such as metallic cover plate and several underlying insulating mats ...