A circumference of chromed or satin metal with a circular diffuser, formed from a pair of cast, sandblasted and tempered glass lenses, two apparently simple elements that hide a complex system. The adjoined convex lenses are in fact held in place by a system of small clamps and fixed to the metal structure with two pins, the same on which the light source is also mounted. The diffuser can thus rotate on itself and orient the light flow in different directions.