The piece has an air inlet (12) which redirects a cassette in the conveyor. The cassette passes through an outlet (14) via a passage (16) with a flexible wear-resistant lining (18,20). The flexible lining is partly made of a rubber lining. The outer part (18) of the passage is a rubber-elastic baffle whose outer face rests on a series of supports (40) resting against the outer wall.
