I have 2, both SII Big Sky, a 3-9x42 and a 3-12x42. I also have a Zeiss, and optically I would put them right there with it. They smoke my Leupy VXII and Nikon Monarch. They have the optical quality of the Euro glass with the weight of a Leupold...best of both worlds IMO. They are the truest tracking scope I have ever used, and so far they have held zero perfectly, but I have only had them since before deer season, so I cant really compare durability to my other scopes.