Method Seven glass lenses were developed so people who work under High Pressure Sodium Lighting (HPS) can protect their eyes and see natural colors. HPS lights are the most efficient and powerful light sources on the market for growing indoor plants. However, because these lights make everything look yellow, it is nearly impossible to evaluate the well being of plants when viewed under this lighting. Using Method Seven lenses you can see the natural colors of plants being grown under HPS Lighting conditions. There are also benefits for glass blowers in some applications (when light intensity isn't too high).