Developed by NASA, Nastek Plant Stress Detection Glasses allow one to identify plant stress or disease 2-10 days before it's visible to the naked eye, so there's time to react. The special lenses block out the green reflected by the chlorophyll in healthy vegetation, causing them to look black or gray. Any off-colors caused by drought, disease, poor nutrition, or other harmful conditions stand out against this dark background. The product works best on sunny days, which enhances the contrasts. Case and additional sunglass lens (for UV protection) included. This could help persons with mobility, endurance, and lower extremity limitations to better monitor their crops.