I am biased, I admit, but the Schmidt &Bender 3-20 is the HEAT!! Fantastic magnification range, no tunneling, smaller than the 5-20, but possibly more useful. I have the 3-20 as well as the 5-25, and I THINK, I'm liking the 3-20 more. I run mine on my gasser GAP10, and couldn't be happier.