It is the channel connecting the main channel and each cavity in the multi-slot die. In order to make the molten material fill the cavity at equal speed, the arrangement of the runners on the mold should be symmetrical and equidistantly distributed. The shape and size of the runner section affect the flow of the plastic melt, the release of the product and the ease of mold making. If an equal amount of flow is used, the flow path resistance with a circular cross section is minimized. However, due to the small specific surface area of the cylindrical flow passage, it is unfavorable for the cooling of the diversion channel material, and this diversion passage must be opened on the two mold halves, which is labor-consuming and difficult to align. Therefore, trapezoidal or semi-circular cross-section runners are often used, and they are opened on half of the mold with a stripper rod. The runner surface must be polished to reduce the flow resistance to provide a faster filling rate. The size of the runner depends on the type of plastic, the size and thickness of the product. For most thermoplastics, the cross-sectional width of the runners does not exceed 8mm, extra large up to 10-12mm, extra small 2-3mm. To meet the needs of the premise should be reduced cross-sectional area as much as possible to increase the shunt material and extend the cooling time.