The adidas X-21 Cross Trainer is ideal for all-round fitness, allowing you to build muscular and cardio endurance without having to put impact strain through sensitive joints. The rear-drive 10 kg / 22 lb flywheel is efficient at storing kinetic energy, which in turn maintains momentum and creates a smooth, quiet elliptical motion. You can easily adjust the intensity of your workout by using the quick resistance keys located on the fixed handlebars to select one of the 24 levels of electronic resistance.