Seems to me it kinda like the Scope "Multipliers" you can buy that are suppose to make your target appear larger. I bought a few and frankly was disappointed as they tend to distort a larger target rather than make it larger while maintaining clarity. Some guys like them and they say work for them, while others think they are BS and a waste of money. I believe you are much better off buying a good, more pwoerful scope with better clarity. I find that to be the case when I compare some of my "quality" 36X scopes to a "good deal" 36X scope that'll get you close. But then "close" also only applies in horseshoes and hand grenades.
Alex
I bought a Bullseye from Gene Davis wen they came out about 10 years ago. Tried it on 36 power Weaver and Leupold scopes. What I found was that past 200 yards, the image was too blurred to see scoring rings. A friend of mine at the range looked thru the Bullseye also and had the same impression. I returned it for a full refund.