I run a very busy fish & chipper in Adelaide, and we used to have our ducting and canopy behind the filters cleaned every 6 months and the filters changed every month. Since getting the Shepherd Filters nearly 7 months ago, we only need to have the disposable filters removed and changed every 6 weeks. The ducting and canopy area behind the filters is still as clean as it was 7 months ago. I am pleased I went ahead with this product as it is not only saving me money, but also the inconvenience and hassle of the duct cleaning. I would be happy to recommend this product to others in the industry or anyone with a commercial kitchen.