Reactive silencers are usually only made of sheet metal or stainless steel and do not contain mineral wool, because in specific industries porous materials are avoided for hygienic reasons. However, this also creates a larger construction. The advantage is that it can be completely cleaned with disinfectants or steam cleaned. The silencers pictured here are located on the roof of a manufacturer of a nut-cocoa-spread which causes sticky particles in the exhaust air.