Brand new, unopened. Product information is listed below. Thank you. ✅【What is a core bushing?】 Bushings determine the steering feel of a skateboard. Their structure and hardness affect the movement, and fine adjustments can be made by tightening the kingpin nut. Core bushings have a two-layer structure made of different materials, and when the deck tilts beyond a certain point, they prevent excessive tilting compared to standard single-material bushings. ✅【Wheelbite Prevention】 When turning or landing, if the deck tilts too much, it can hit the wheels, locking them up. This is called "wheelbite" in skateboarding and is the enemy of skaters. Using core bushings softens the movement of the trucks, allowing the skateboard to move more freely while reducing the risk of wheelbite. Many top pro skaters and super kids use them. ✅【Product Contents】 One set for one skateboard (upper and lower bushings for two trucks), including 2 upper bushings with a thickness of 11mm and 2 lower bushings with a thickness of 14mm, for a total of 4 pieces. ✅【Material and Hardness】 The core uses strong polycarbonate, and the urethane part uses high-rebound SHR urethane for a responsive feel. Choose from two urethane hardnesses: soft 85A and hard 90A. Softer 85A is recommended for young children, those with weaker leg strength, or those with lighter body weight. For general adults and those who prefer a harder setting, 90A is recommended. Also, you can maintain a similar feel throughout the year by switching to 90A in the summer and 85A in the winter.