Difficult to Determine
It arrived promptly and was packaged well. I like the little box and its recessed insert. I live in a city of 1.8 millions and I am in town, with skies Bortle 7-8. Viewing the Sadr and Deneb regions in Cygnus, I did not perceive much difference with or without the filter.
L-Pro all the way
I find that the L-Pro is great for imaging galaxies, clusters, and some nebulae in my backyard, which is Bortle 5. I even got great results last time out with a significant amount of moonlight present. Emission nebulae are better handled with the L-eNhance filter.
Great LP Filter!
I have both the 1.25" (for my filter wheel) and the 2" for my DSLR and I really love both of them. They are great for helping to cut out the light pollution is the Austin suburban skies (Bortle 8) where I'm at. There are a lot of other really great filters out there, but so far my experience with the L-Pro has been top notch.