This 7"dia silencer uses a single polished skin of 0.9mm Stainless Steel. Packed with hi-tech materials including Acoustafil wrap it is quiet enough for most UK tracks but with a single 2.5"dia tailpipe you can add an extra add-on silencer for those really strict tracks. Alternatively, you can run with my Silenced De-Cat Pipe (SDCP) to reduce those decibels.