Round wire spring, also known as coil spring, is a kind of compression spring and compression spring, and it is the most common type of spring. The cross-section is circular, and the main functions are rebound, shock absorption, and thrust. When the spring is a linear spring, spring load (N) = fixed number (N/mm) x compression (mm). The materials are made of piano steel wire (SWP) and stainless steel wire (SUS304). The heat resistance and load level are different. The specifications have both ends flat and no flat.