Removable solar iris diaphragm holder for D-ERF 70/90/110 filter mounts ; Required to use infinitely adjustable iris diaphragm 13 - 113mm (#2459300) ; Suitable for the sizes 75, 90 and 110mm of the filter mounts for D-ERF energy protection filters 75-180mm (different versions / variants available);
For optimal adjustment of a telescope aperture when observing with an H-alpha surface filter from SolarSpectrum (also suitable for other brands) ; Made of CNC-milled aluminum.