• 1.25-inch variable polarizing filter for astronomical telescope eyepieces. • Allows light transmission to be adjusted from 1% to 80% by rotating the filter housing. • Reduces glare and increases contrast for clearer lunar and planetary observation. • Neutral color optical glass that does not alter the natural color of the lunar surface. • Standard 1.25-inch thread (M28.5 x 0.6) compatible with most eyepieces. • Provides precise brightness control for optimal performance in observation and photography.