LUNT LS100FHa (0550400) The Double-Stack Etalon Solar-Filter for all LS100FHa Filter and LS100THa Telescopes. LS100FHa Main Filter Transport case Double-Stack Etalon for all LS100FHa filters and LS100THa telescopes. Adding this additional Double-Stack etalon system will reduce the bandwidth to <0.5 Angstrom (dependant upon used telescope). So you will have much more contrast and more details on the sun will be visible. Technical data: Aperture: 100 mm Bandwidth double stacked: <0,5 Angstrom Tuning: tiltable Etalon Housing diameter: 162 mm Length: 101 mm Front thread: M120x1.5 female thread Rear thread: M120x1.5 male thread Without Blocking Filter! Only for use as double-stack filter, or together with a additional available blocking filter. If the filter is used only single stacked together with a optional blocking filter, then the bandwidth is <0.7 Angstrom.