Plain torque tube set is 4-1/2" long with an outer diameter of 2-1/8" for use in 2-1/4" inner diameter straight pipes. Set will fit into 2-1/4" inner diameter straight pipes. The unique shape will compress exhaust gases for more sound and less noise with added power. Requires one 1/4" hole for mounting. Sold in a quantity of 2. *Baffle diameter denotes the size of the pipe into which it fits. Fits: Custom application for straight pipes