Demand for fine springs is rapidly increasing in applications such as connectors, medical catheters and so on. Among them, the smallest springs are used in devices for semiconductor testing, with 0.072 mm of coil diameter and 0.015 mm of wire diameter, one of the smallest springs in the world. Mikuro’s super fine springs have high strength and long life, hence have always been desired by customers. We are now developing springs with 0.065 mm of coil diameter.