Nastek Turf Stress Detection Glasses (developed by NASA) identify grass, plant, and tree stress and disease before their effects are visible to the naked eye. Shatterproof polycarbonate safety lenses block out green spectrum reflected from chlorophyll found in healthy vegetation so it appears black or gray. Off colors from weeds, drought, disease, pests, and poor nutrition stand out as glowing red, coral, pink or yellow colors against the dark background, enabling targeted treatment of problem areas. Also checks mower cut quality and blade sharpness, and identifies mowing patterns on turf, fairways, and greens to reduce overlapping. Quick-change lenses for turf stress, sun protection (flame copper), and low-light (yellow) snap into wrap-around sport frame. Turf Stress lenses also are available in clip-on glasses and in 72-mm., hand-held camera lens filter for digital and film cameras used to document conditions photographically. Items are available separately or in combination Pro Pak with carry case and turf detection guide.