This OVL Long-Pass Telescope Filter limits the transmission of light longer than 650 nm. While blocking all other light pollution, this filter allows emission nebulae to be observed in the telescope with significantly increased contrast. It is therefore ideal for emission nebulae and objects that radiate in the H-alpha range. It only makes sense for CCD photography. Scope of delivery: Filter 1.25″ storage box! Power supply and batteries are not included!