Loading Grade : Light LoadHole Diameter (OD) : 8mm/0.31 inch;Rod Diameter (Inner Dia) : 4mm/0.16 inchFree Length : 20mm/0.8 inchProduct Name : Die Spring; Rectangular Section. Die springs are primarily used in die machinery.For die springs, yellow color here represents that the loading grade is light load.Additionally, we want to tell you: in the yellow, blue, red, green, brown die springs, YELLOW ones are the lightest load ones.However, because die springs are well suited for high stress applications, they are also suitable for a variety of other applications as well.Hole Dia: The Diameter of the Hole on the Mold ,.the Outer Diameter of the spring.Rod Dia: The Diameter of the Rod that is to be inserted into this spring, .the inner Diameter of the spring. Colour:yellowMaterial:Spring steelPackage Contents:20*Die SpringOnly the above package content, other products are not included.Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.