Abstract: A replaceable screen structure for a stock screen where stock slurry for making paper is passed through a screen with the rejects going to a reject outlet and the accepts passing through openings in the screen to an accepts outlet, with the screen having projections and a rotor inducing a pulsating induced flow along the profile surface, with projections on the surface having an inclined ramp of less than about 45.degree. and a 90.degree. downstream wall and accepts flow openings between the projections positioned closer to the upstream projection than the downstream projection.