Helping a senior downsize and posting a number of camera and telescope items for him.
This is a Lumicon 72mm H-Alpha Night Sky filter kept in plastic case.
Per manufacturer:
Lumicon 72mm Night Sky Hydrogen-Alpha Filter
NOT safe for Solar Viewing! Do NOT view or image the sun with this filter!
Lumicon 72mm Night Sky Hydrogen-Alpha Filter is ideal for black & white deep sky photography. The filter is an extreme anti light-pollution filter, and allows for contrast-enhancement of emission nebulae and other astronomical objects bright in the infrared.
Lumicon 72mm Night Sky Hydrogen-Alpha Filter is long-pass with a 50% transition from blocking to passing at about 640nm. At wavelengths longer than 650nm, transmittance is 90% or above. The filter is an extreme anti light-pollution filter, and allows for contrast-enhancement of emission nebulae and other astronomical objects bright in the infrared.Threaded for 72mm camera lenses.