SPRING KIT: This Assorted galvanised Spring Set includes 200 pieces extension springs and compression springs.The extension spring can absorb and store energy, and the compression spring has the opposite effect when there is pressure. DIFFERENT SIZE: 200pcs/Set Assortment Box Spring has Spring assortment of different size will meet you different demands.And it also has good mechanical properties, toughness and strength are relatively good. SOLID AND STURDY: With Tension Springs Coil Spring made of high quality material, solid and sturdy to use.Moreover, the compression spring has played a role in slowing down the vibration to a certain extent. GREAT RESILIENCE: Assortment Tension Spring has great resilience and for durable use, greater resistance to corrosion.It can run cyclically, as long as you give it a force and don't stop, the machine will continue to operate. SCOPE OF APPLICATION: Tension Steel Spring an essential hardware for various repair and maintenance in vehicle, electric appliance, digital devices, etc.Install a compression spring, you will find that its speed has been greatly improved when it is driven, and there is no sound during the movement.