We manufacture several different types of shutters and louvres, fixed and adjustable blade options and our own design for adjustable blade situations - McVENT. MJN McNaughton McVENT Cedar louvres available in: - fixed blade (different sizes) - adjustable flat (2 sizes) - adjustable aerofoil (2 sizes) - closed louvres (2 sizes) McVENT 38mm x 10mm blade. These are able to adjust in full open positive without protruding past a 40mm thick shutter. This allows the shutter to slide away with no worry of hitting blades on windows or walls.