Specialized displays and visual indicators are specialized or proprietary products and accessories related to displays and visual indicators. There are many different types of specialized displays and visual indicators. Examples include a head up display, visual approach slope indicator, brake indicator, and pneumatic visual indicator. A head up display is a type of specialty display that provides means of projecting information directly into a human's visual field. A visual approach slope indicator is a type of visual indicator that provides special lights on the side of a runway to assist pilots with staying on the glide slope for the runway. A brake indicator is a type of visual indicator that signals either a parking brake is engaged or that brake fluid is low. A pneumatic visual indicator is a type of visual indicator used as an accessory to provide a quick and reliable, visual indication of the status of a pneumatic system and detects the presence or absence of a pneumatic signal. Other specialized displays and visual indicators are commonly available.