Slide is protected against pollution, dust, fingerprints and scratches. The air exchange system enables the slide to "breathe" which helps to eliminate bacterium and Newton rings. The Anti-Newton glass prevents Newton rings. The mount prevents penetration of dust. The slide is safely held in place with the clips of the metal-mask. The slide stays absolutely flat to ensure a focused projection of the whole image. The edges of the metal-mask ensures absolutely sharp edges around the image.