RF energy is part of the electromagnetic spectrum like visible light. RF devices can be classified in 2 categories: monopolar systems and bipolar systems.Electro-optical synergy (ELOS) is a novel technology that encompasses a unique blend of optical and electrical radiofrequency (RF) energies simultaneously applied to tissue. RF can be used alone or combined with optical energy in skin rejuvination and resurfacing, in acne vulgaris treatment , in photoepilation of white and blonde hair, in cellulite reduction & in treatment of vascular lesions.