Sometimes less can mean more! O- and Z-rings have been dispensed with completely on this chain specially developed for motocross use. Minimal loss of power and good durability. Fits on 50 SX Junior 2007, 50 SX Junior 2008, 50 SX Junior 2009, 50 SX Junior 2010, 50 SX Mini 2008, 50 SXS 2011, 50 SXS 2012, 50 SXS 2013, 50 SXS 2014, 50 SXS 2015, 50 SXS 2016, 50 SX Factory Edition 2021, 50 SX Factory Edition 2022, 50 SX Factory Edition 2023.