Fine brightness control for 51 mm eyepieces and accessories - Provides finer control of image brightness compared to fixed-transmission filters, enabling precise, high-contrast views. - Compatible with 51 mm eyepieces and accessories for easy integration into your observing setup. - Reduces the brightness of the Moon or planets to achieve a clearer, more detailed view. - Light transmission is adjustable from 1% to 40% by rotating the filter housing for quick, on-the-fly tuning. Applications and scenarios - Moon observation: balance brightness at the terminator to reveal crater details without glare. - Planetary viewing: enhance contrast on Jupiter, Saturn, and other bright planets to see subtle features. - Bright-sky observing: in light-polluted environments, dim the view to improve comfort while preserving detail.