JBI Pro Perch http://www.ridejbi.com/jbi-pro-perch/ Specifically designed for KYB, Showa, & WP Twin Chamber Forks Exclusive Pressure (Speed) Sensitive Damping Design Improves fork bottoming control giving you confidence to go BIG Enhances fork feel & plushness through out the entire stroke Developed for MX, Off-Road, & WORCS riding/racing Simple installation with factory level results Replaces stock spring perch Instructions & setup tips included Sold as set Patent Pending Made in the USA What Is the JBI Pro Perch? The JBI Pro Perch is a high performance replacement spring perch for KYB, Showa, & WP Twin Chamber forks. How Does the JBI Pro Perch Work? Unlike stock spring perches that feature "fixed" holes for oil to simply flow through, the JBI Pro Perch is pressure sensitive meaning the port area (hole size) for fork oil to flow through is based on pressure. (Small pressure = small port area / High pressure = large port area). This "active" style of damping at the spring perch results in a fork that is plush on small bumps yet firm enough to soak up those hard hits & landings without being harsh.