Spring pins (clamping sleeves) light version ISO 13337-spring steel plain 4x20

Spring steel is a steel that has a higher strength compared to other steels, but with very high elasticity. Tension discs and disc springs are made of spring steel so that the spring forces defined in the standard can be achieved.

The term plain indicates a completely untreated, merely oiled, smooth surface for all DIN and ISO screws such as wood screws, hexagon head screws, threaded rods, nuts and many types of washers.