These have removable discs to dial in back pressure. Fits Hot Rod # CPR251116-HR.
Spark Arrestor Stainless Steel 4 inch Fits Sand Rail # CPR251116-SR
4 inch Stainless Steel Spark Arrestor Fits Race Car # CPR251116-RC
4 inch Stainless Steel Spark Arrestor Fits Dune Buggy # CPR251116-DB
Stainless Steel Spark Arrestor 4 inch Fits Rat Rod # CPR251116-RR
Weld On 4 3/4 Inch Disc Spark Arrestor Fits Dune Buggy # CPR251115-DB
Spark Arrestor 4 3/4 Inch Disc Weld On Fits VW Sand Rail # CPR251115-SR