I have to agree with Redhawk & Victorharlie, the only time I will use see thru mounts, is on a combo rifle/shotgun weapon that doesn't shoot both barrels to the same point of impact, and I still don't like them. As long as you use a low power variable, such as a 1.5, it really negates the need for iron sights anyways.
Sincerely,
Garry