Description: Material - Our spring part is constructed from spring-steel with high manganese and high carbon, which has high resilience and strong toughness, corrosion resistance, and solid structure for added durability. The spring features a high arch and short spacing design, sufficient material, and stronger supporting force. Wide Application - The couch spring set is commonly used in making new/replacing old furniture upholstery, sofas, chairs, recliners, dining chairs, and even automotive seats. In addition, it is more economical to replace a spring for an old sofa or sagging seat than to replace a new couch. How to Choose Spring Length - Disassemble the bottom of the sofa, and you can see the position where the inner frame installs the spring; Measure the distance between the edges of the wooden frame which would attach the spring; If in between the whole numbers, we recommend rounding off to the nearest whole inch/centimeter. Notice - Please be careful and wear gloves when installing the spring. If there is no repair experience of the sofa, it may take two people to complete it.