This UV-IR Cut Filter has an unmatched 98% Average Transmission! Freedom from ghost images (very low reflection multi-coating, Striae-free, and plane-parallel substrate).
Extremely Sharp Cutoff at 690nm (leaves all the visible red, including the important 656nm H-alpha emission line).
This UV-IR Cut Filter has a sharp cutoff below 400nm. Eliminates violet halos around bright stars (more effectively than simpler so-called Minus Violet photographic filters).
(Please note that FW5-STX is now obsolete. Use 50 mm square filters for the FW7-STX.)