Great resilience and for durable use. Greater resistance to corrosion. -Used for automotive engines, major appliances, medical devices, electronics, and sensitive measuring instruments. 200PCS Spring assortment Spiral Spring Galvanized Spring Set Spring Rate Extension Spring. This item is spiral springs that offer resistance to a tension force, or load, applied along the axis of the spring. When a load is placed on an extension spring, making it longer, the spring pulls back against the load to return to its original length. These springs are used in a variety of applications, including automotive engines, major appliances, medical devices, electronics, and sensitive measuring instruments. Description: Material: metal Color: silver Pressure spring: 7*13=10, 6*12=Only, 5.5*27=10 9.5*16=6, 9*18=12, 9*35=8, 5.5*38=10, 7*19=10 Pull spring: 5*10=10, 5.5*14=10, 6*10=10 8*13=8, 7.5*17=10, 8.5*26=12 8*50=12 Only (without ears) 7*55=12, 4*70=12 5*34=8, 7*25=10, 8*23=10 Notice: 1.Please allow 1-3mm error due to manual measurement. pls make sure you do not mind before your purchase. 2.The colors may have different as the difference display,pls understand. 3.Please leaving a message before you give the bad feedback, if the products have some problems. Packing list: 200Pcs/box * spring *