Loading Grade: Light Load Hole Diameter (OD): 8mm / 0.31 inch Rod Diameter (Inner Dia): 4mm / 0.16 inch Free Length: 20mm / 0.8 inch Product Name: Die Spring Rectangular Section Die springs are primarily used in die machinery. The yellow color indicates a light load grade. Among yellow, blue, red, green, and brown die springs, yellow springs have the lightest load capacity. Due to their high stress resistance, die springs are also suitable for various other applications. Hole Dia: The diameter of the hole on the mold, corresponding to the outer diameter of the spring. Rod Dia: The diameter of the rod to be inserted into the spring, corresponding to the inner diameter of the spring. Color: Yellow Material: Spring Steel Package Contents: 20 x Die Spring Note: The package includes only the items listed above. Other products are not included. Lighting and display differences may cause slight variations in color between the image and the actual item. Measurement error allowance is +/- 1-3 cm.