What's the difference between an AC Vent Cover and a Linear Slot

What's the difference between an AC Vent Cover and a Linear Slot linear slot grilles Linear type diffusers and grilles have been developed to satisfy architectural and engineering applications that require a continuous length appearance, linear slot drainage channels Pristine white, 1 wide linear slot diffuser with concealed mounting Features Extruded aluminum construction; 12, 34 and 1 slot widths; 1-8 slots

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linear slot diffuser catalogue Bradflo U-Blade Linear Diffuser 1 Slot Complete 1000mm Product Code: 3204031  Bradflo U-Blade Linear Diffuser 1 Slot Complete 1000mm Product Code: 3204031