F.O.L.™., a system of filters in polyethylene terephthalate that ensures a clean light beam while guaranteeing excellent optical efficiency. The filters, installed in direct contact with the lighting fixture diffuser, define the light beam and optimize it from a physical and visual point of view. The system is made up of 5 filters of different opacity levels and macrostructure composition that are combined together according to the application they are designed for. The F.O.L.™ Filtering Optical Layers patented system is housed in the optical compartment of some families of i-Lèd lighting fixtures, such as downlights, uplights, and wall lights.