The Trail features a soft, flexible, photochromic lens made from NXT® that transitions automatically from Category 1 to dark Category 3. Ultra-clear when unactivated, the Zebra Light lens offers excellent visibility in very low light conditions and darkens extremely quickly to protect the eyes when exposed to full light levels. *Lightweight: weighing in at an impressive 1 oz., this model is ideal for running and cycling. *Flexible lens: Julbo is the only sunglass manufacturer utilizing the flexible lens material. *Ventilation: adjustable natural airflow with 2 positions due to the cut of the lenses. *Comfort: supple shock-absorbent insert will remain in position on nose. Elastomer shock absorbers at sides for maximum protection. Elasticated extra-flat cord.