These high-quality OVL telescope filters made of optical glass in a black anodized aluminum frame reduce the light entering the eyepiece through variable polarization. You can progressively dim the light when observing bright objects like the moon or some planets to the level that suits your needs, thereby increasing contrast and eliminating glare to see more detail. The light transmission can be variably adjusted between 40% and less than 1%. The filter does not change the color of the observed object and prevents eye fatigue and loss of night vision. Each filter set consists of two polarizing filters, one of which can be rotated to adjust the brightness. The filters can also be used individually, for example to reduce light reflections from water surfaces or glass during daytime observation. Scope of delivery: Filter 1.25″ storage box! Power supply and batteries are not included!