The H-alpha Narrowband filter transmits only H-alpha wavelength light, which is found in most nebulae, star clusters, galaxies, and stars. This makes these filters ideal for complex false color imaging of such regions. H-alpha filters such as this one are excellent for boosting contrast and are most definitely a must-have for imaging in areas with high levels of light pollution. This particular H-alpha filter has a bandwidth of 7nm. Unmounted, this filter will fit into filter wheels made to accept 36mm filters.