As stated above, the screw-in 2x magnifier is an economical option for the HD7 if you need just a little more reach from your optic however, in my case, it drastically reduced the field of view through optic which makes looking through it feel awkward.
Pros: Economical upgrade to the HD7.
Cons: Drastically reduces field of view through optic.
This review was written in the old system and had content requirements that are different than reviews written today.