What normally appear as subtle grey stripes, illuminates with reflected light when exposed to a direct light source. The stripes are created by tiny retroreflective lenses on the surface of the fabric. The stripes reflect different shades depending on the intensity of the light.
Retroreflective is directional, reflecting light only toward the light source. It’s like wearing a secret. The retroreflective can only be viewed from the same direction as the light source (ex. making sure that your eyes are in front of or behind the light source). The way you see the stripes, may be different from how your friend sees them, depending on where you are standing in relation to the light.