Overall I think that this is a good quality barlow. Lots of power so you need a lot of light. Minimal refocusing needed when combined with other Celestron X-cel eyepieces.
This 3x Barlow lens is durable, crystal clear, and super easy to use. I was surprised that it didn't seem to dim any planetary or lunar views, and I was able to use it successfully for astrophotography. All my 1.25" eyepieces fit perfectly and lock in place, as well as my prime focus/T-ring adapter. It doesn't have a protective cap like most eyepieces, but it still has the securable insert like most focusers and eyepiece adapters have, so it still keeps out dirt. I would definitely buy this again. The icing on the cake is that OPT got it to me very quickly!