PROMASTER uses only the finest optical glass in the Infinity series. Coatings make all of the difference when you want a bright crisp image and PROMASTER has spared no expense here. These glasses feature PROMASTER's EXCLUSIVE TRANSBRIGHT™ 99.3% light transmission coatings for the ultimate in bright, crisp images as well as PROMASTER's EXCLUSIVE REPELLAMAX™ element repellent coatings that aid in keeping your optics free from dust and other environmental elements to ensure you get the maximum viewing enjoyment and capability from your binoculars. Every optical glass surface is fully broadband multicoated. This is not true of many far more expensive binoculars. The prisms are specially selected BAK-4 glass that has been both phase and silver coated to ensure true, sharp images. The ocular of every model has the maximum eye relief possible. This enhances the brightness and viewing ease.