A system for forming a product from a food mass. The system includes a mould member having a multitude of cavities, in which the food mass is formed; and a feed channel that feeds the food mass into the multitude of cavities. The system includes an insert to alter the width of an exit of the feed channel. The feed channel includes an upstream edge and an opposing downstream edge, and the insert is connected to the upstream edge. The insert has a straight section that contacts the food mass flowing through the feed channel. The straight section is located downstream of a section of the insert that is tapered. A width of the feed channel in a region of the section of the insert that is tapered is greater than a width of the feed channel in a region of the straight section.