When the sliding clip moves forwards, its wedge shape inside the shelf support applies a pressure against the two zinc alloy ridged wings. Quicker installation of the shelf; just place in the required position the shelf supports with the wings already spread and then push downwards the shelf. The ridged wings grip into the chipboard and lock the shelf in position. Easy repositioning of the shelf; just move backwards the sliding clips through the fingernail or screwdriver blade sockets, the wings retreat. Push upwards the shelf to release. For shelf minimum 15mm thick.