ENHANCED CLARITY - Blocks yellow light from sodium-vapor lamps, mercury-vapor lamps, or low CRI LEDs, reducing light pollution for clearer night sky images and videos. SUPERIOR OPTICS - Crafted from H-K9L optical glass, this 72mm filter ensures optimal light transmission and minimal distortion, maintaining the highest optical quality. VERSATILE COMPATIBILITY - Features a 72mm front filter thread size, making it easy to attach to lenses and front lens caps of the same size for seamless integration. OPTIMAL BLOCKING - Experience effective light pollution reduction with a density of 0.2 to 0.45, providing a filter factor of 1.5 to 2.8 (0.6 to 1.5 stop).