This is a pack of 3 Diffuser Discs for the SuperTrapp 5S Series Spark Arrestor Mufflers (sold separately). Typical installations should use 1 disc per 7 horsepower for proper back pressure (e.g., a 20 HP engine should use 3 discs; a 85 HP engine should use 12). Using fewer discs will further reduce noise but will also cause some power loss. More discs should be used on engines rated below 2400 rpm, or if the 5S will be used in conjunction with an existing muffler.
SuperTrapp mufflers are the only USDA Forest Service Approved spark arrestors that do not rely on restrictive swirl baffles or fragile screens. Sparks are funnelled into a collection chamber in the end cap, while exhaust gases exit between special diffuser discs. Even if the collection chamber filled to capacity, the small 0.023" gap between the discs still provides a back-up layer of spark protection.
The 5" diameter SuperTrapp 5S Series muffler is recommended for engines up to 100 HP, but it can also be used on engines up to 200 HP where compact size is a greater concern than noise reduction.