I've got the 20-60x86mm version. I has a removable eyepiece with attachment lugs that resemble the Razor Gen 2 eyepiece or maybe the Burris signature HD eyepiece, but I don't know anybody with an Athlon, Vortex, or Burris that I can compare with. It resolves decently across the range, but the image does darken noticeably from 50x to 60x. Eye relief is probably the 18-20mm as advertised but because of the way my eyes are set in my melon, I still end up crowding the eyepiece a little at higher power. It's pretty decent for the money if you catch it on sale. I'd like to compare to a Razor if I ever get the chance.