Orion 4-Filter Wheel for 1.25" Filters 4-Filter Wheel lets you rapidly switch between four different 1.25" eyepiece filters without removing the telescope eyepiece! Wheel holds up to four 1.25" eyepiece or astrophotography filters, and allows manual toggling between installed filters via a knurled wheel Great for planetary observers - install up to four color filters to tease out low-contrast planetary details and features Deep-sky observers can install up to four different filters, such as an O-III, H-beta, Ultrablock, and more, to enhance views of "faint fuzzies" (filters sold separately) Requires an additional 20mm of back focus travel - ideal for use with any refractor or Cassegrain telescope, and most reflector telescopes