Multimode, step-index optical fibers offer the most efficient and flexible delivery of high power laser beams. The correct components should be selected for minimizing beam quality degradation and optimum robustness. Smaller fibers tend to produce less degradation to beam quality but the minimum usable fiber size is limited by the quality of the laser beam, focusing optic and the numerical aperture (N.A.) of the fiber. Selection of the appropriate fiber type is an important consideration because the characteristics of the output beam will enhance or degrade the utility of the fiber optic delivered beam for different applications. The other components of the beam delivery system also impact performance: High power handling requires high quality end face surface finish and specially designed connectors that can withstand heating which comes from the absorption of spurious reflections at the fiber end faces. The fiber optic delivery system allows the laser beam to be transmitted in a small, flexible cable and is ideal when the laser beam must be delivered along a complex path or processing requires complicated manipulation of the beam delivery optics.