Four-Way square diffuser for air supply-return with connection plenum box incorporated. The DRIM series modular diffusers are designed to be applied in air conditioning ventilation and heating systems. This sort of diffuser can be used in premises from 2,6 up to 4 meters high and with a temperature differential up to 12º C, obtaining good results, not only in air speed but also in sound pressure level in the comfort zone. The DRIM diffuser causes a 4- way horizontal air supply with coanda effect and the air return is done through its inner core. The perforated face in air return is hinged removable core without tools, by pressing on the invisible PUSH fasteners. KLIN system allows for the easy access to the diffuser that conform with the required regulations for maintenance of HVAC installations. The DRIM modular diffusers meet the functional requirements of modern updated locations. Its design fits perfectly in the technical false ceiling.