Originally Posted by MAX-nz
I have a 3x and a 4x - both in the universal fitting.
I use the 3x on the back of my Leopold 6-20 EFR and absolutely love it.
I found the 4 times didn't allow the ocular bell to be adjusted in enough on the Leupold to allow the crosshairs to come into sharp focus.
Warning - they will reduce your eye relief to less than half of normal.
But I found that is a good thing because it required the scope to be moved back thus enhancing balance.
There is a very slight loss of resolution, but barely noticeable with a good quality scope such as a Leupold.
I don't know how to measure it exactly, but it is rated to add around 30% more magnification to any scope.
3x's = plus 30%. 4x's = plus 40%, so the literature advises.
I recommend the 3x's highly.
Agree with all of that apart from I have the 4x target I think and although I couldn't initially seem to get it to focus as crisp on the crosshair as I wanted by adjusting the occular bell to its maximum adjustment all of a sudden it is now crisp(don't understand) use it on an 8-32 x 40mm 4200 Bushnell for .22 rimfire benchrest indoors loss of light is minimal, don't know how they achieve such a boost with clear image. Getting a screw in one for the T36 next.