Magnetic and magnetic-based devices, apparatuses, components and modules, namely, magnetic shaft couplings for machines, for improving the efficiency and performance of generators, alternators, engines, electric motors, transportation vehicles, vehicles for transportation over land and air and water and space, wind turbines, rotating machinery, rotating equipment, compressors, chillers, turbines, pumps, fans, blowers, gearboxes, motorcycles, electric motorcycles, bicycles, e-bikes, skateboard...