[Shock Absorbing Spring] This car bolt is different from similar products in the market, we also specially equipped with springs, the springs can absorb some of the vibration, reduce the impact of vibration on the fixed parts, prolong the life of the parts. In high temperature environments, the bolts with springs can compensate for this change through the compression or extension of the spring, maintaining the sealing and stability of the system. [Fixed Exhaust Gasket] Car bolts are one of the key components to keep the exhaust system working properly, when being tightened, it exert enough pressure on the gasket to enable the gasket to form an effective seal to keep a tight contact between the two to avoid leakage and to keep the engine running with a tight seal. [High Temperature Steel] Since the working environment of the system is very rough, including high temperature and vibration, our car bolts are produced by manganese steel and steel which are high temperature materials, even under the rough conditions, the car bolts can keep the performance, which makes the system run more stable and efficiently and safely. Please note:the physical slightly color difference or difference, does not affect the use, please do not mind, thank you! Colour:As Shown Material:steel Package Contents: 2 x Car Exhaust Manifold Bolts Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is 1-3cm.