SV191 7.2-21.6mm zoom eyepiece--Maintaining parfocality allows you to run through the focal length range without the need to refocus after each new magnification is set. But minor tweaking is necessary. SV165 Mini Guide Scope Support sensitive auto guiding cameras for easy guide star acquisition. 45mm Tube Travel. Improved image adjustment accuracy. For clearer images when used with astronomy cameras and telescope eyepieces. SVBONY Universal Dovetail Base is compatible with finder scope; can be installed on telescope; Compatible for Clestron Orion Sky-watcher Vixen and so on. 1.25in diagonal fits telescopes with 1.25in focusers. Accepts standard 1.25” eyepieces, filters, Barlow lenses and other accessories with a 1.25in insert barrel. UHC filter,basically, it works by darkening the background so you can see more nebulosity that would otherwise be too faint. This filter allows one to really see small planetary nebulae that would otherwise be washed out by the background, such as the M42 Nebula, the Dumbbell Nebula, and the Lagoon Nebula.