Astromania 1.25" Variable Grey Polarizing Filter Allows for selective adjustment of brightness which is useful for terrestrial observation and objects of the Solar System. You often find considerable differences in detail brightness on objects of the Solar System. This is particularly noticeable when observing: - Moon craters which are close to the lunar terminator - Sun spots and faculae. Caution: only to be used in association with an appropriate solar filter on the front of your telescope! - Details on planets Irradiation from brighter regions prevents you from distinguishing fine details. Variable polarizing filters allow you to selectively adjust the level of darkening. Light transmission: Light transmission of polarizing filters is between 1% and 40%. These filters have a very large range of effectiveness. Handling: Variable polarizing filters are made up of two individual filters. The variable darkening effect is produced by rotating the lower filter relative to the upper one. Capacity: Connection(to the telescope): 1.25" Type: Polarizing filter Mount material: Aluminium Color: neutral grey Transmission: 1(variable from 1% to 40%)