There are differences in Burris fullfield scopes, the original fullfield, newer fullfield II and the fullfield E-1. I'm assuming we are talking about the current Fullfield II ? The fullfield II has a different type eyepiece in which the whole eye piece is turned when zooming causing the use of flip up scope cap on the ocular lens is moved also. (basically rear scope cap getting in the way when opened when zooming ) Some other scope models from other manufacturers were also built this way, if not using flip up scope caps then it's no issue. The Burris original and E-1's are a different eye piece zoom design and not an issue. All of the fullfields seem to be decent scopes, not great, but good serviceable scopes that I wouldn't have a problem buying, my son has one. These are just the scopes that I have seen and there could be other design differences built within the years that have changed. Something to look at and read all info before a person buys.