Model FK-1 and FK-19 double-layer adjustable louver supply air outlets match fan coils and central air conditioning terminals, with blades adjustable from 0° to 90° to change air supply range and diffusion angle, and blade adjustment tools are ordered separately. The two models differ only in frame and blade width, FK-19 is narrow-frame narrow-blade type with identical other structures, which can be equipped with split multi-leaf dampers for air volume control and supports various installation methods.