OPTIS (Odyssey Pneumatic Tire Insert System) is a lightweight, highly tunable, high-efficiency, tubeless tire insertDual valve mechanism allows inflating the insert, and surrounding tire to two different pressures where the higher pressure insert supports the tire, and the lower pressure zone improves grip and performanceIf tire pressure is suddenly lost due to a puncture, the interior higher pressure OPTIS allows the rider time to stop without losing controlOptis pressure the tire into the bead, preventing burping as well as helping to seat the bead and easing tire installation and seal27.5x28-40SVUPC/EAN/GTIN: 630950941315