JPH0259716B

A filter for a cigarette includes a porous filter rod circumscribed by a non-porous wrapper provided with at least one groove embedded into the periphery of the filter rod extending from the mouth end thereof a preselected distance longitudinally therealong less than the entire length of the filter rod. Tipping material circumscribes the non-porous wrapper and is provided with flow-through openings therein in flow communication with the groove. The tipping material extends beyond the mouth end thereof defining a recess, and the filter rod includes a cylindrical collar coaxially located in the recess concentrically with the portion of the tipping material extending beyond the filter rod mouth end. The thickness of the wall of the collar is less than the depth of the groove which collar functions as a baffle to accelerate the velocity of the air leaving the groove.