Trimless fully-retractable flush recessed modular system with which to make cuts with a width of 138 or 68 mm in rectilinear, "L-shaped", square and rectangular plasterboard false ceilings and double walls, for direct and indirect, diffused and accent lighting. Consisting of pairs of linear extruded aluminium guides, with a 90° angle and head, with a predefined length and which can be assembled to the desired length, to secure, stucco and smooth in the plasterboard, which can be attached where required: LED linear light sources or battens for T16 fluorescent lamps and double arm swivel projectors, complete with professional LED sources or for QR-CB 51, QR-LP 111, QPAR16 halogen/LED lamps. Fluorescent battens, complete with 50/60 Hz 230/240 V electronic power supply. LED batten with integrated driver. Can be completed with painted metal cover channel supplied in pre-punched stretched sheets for easy shaping by hand on site (occupied volume 110 times less than similar, already shaped channels). To be completed with end caps, opal white PC diffusing screens for LED linear light sources and fluorescent battens and mounting joints.