Baader Premium Eyepiece Filter: Red, 610nm Longpass - 1.25" # FCFR-1 2458307 Freedom from ghost images, even when stacked Striae-free substrates are polished parallel to within 30 seconds of arc to avoid wedge errors Finest 7-layer hard multi-coatings on both faces feature 0.25% residual reflections Extremely high transmission results in maximum contrast and isolation of planetary details, even with smaller telescopes Efficiency of the long-pass filter (Red) peaks at 98%