Teleprompter glass is formulated to let in enough light to allow you to read text with ease without creating a reflection onto the camera screen. The value of teleprompter glass is expressed as a ratio. These ratios are most commonly 70/30 or 60/40. The most typical ratio of 70/30 will reflect 70% of the light from the upside-down text while letting 30% of the natural light through to the camera.\r