A set for mechanical processing suspended fibrous material includes a die plate having receiving openings in a predefined arrangement for insertion of blade-shaped processing elements which jut out on a process side and are flowed onto by the fibrous material. The blade-shaped processing elements have each a plurality of foot regions in longitudinally spaced-apart relation, which pass through the die plate (2) and jut out from the die plate on a process-distal. At least some of the foot regions of the processing elements reach into associated receiving grooves of a base plate on the process-distal side. As an alternative, transverse stiffening elements are arranged substantially orthogonally in the longitudinal direction of the processing elements such that the transverse stiffening elements stabilize the foot regions of the processing elements on the process-distal side.