Alpinestars Rk-1 Plasma Knee Braces Designed for all off-road adventures, the Rk-1 Plasma Knee Brace is engineered for optimal knee support while maintaining lightness, breathability, and protection. It integrates a Nucleon Plasma knee protector within a hybrid frame that blends a flexible composite with a high-performance polymer for exceptional rigidity and flexibility at the straps, ensuring an adaptable and comfortable fit. Sizing: The RK-series size chart that Alpinestars provides suggests sizes that are too small Riders suggest purchasing the same size RK knee brace as you wear in other knee braces Pat from the video has a 4.16 measured knee width and requires a size LG knee brace Features: Ultra lightweight and adaptive Replaceable polyurethane and Nucleon Plasma triple segmented knee cups Self-centering knee cup Slim design four-point hinge system Stainless steel bushings CE level 1 certified Sold as a pair