I bought these to use Weaver rings on my CZ 452 rifle. Unfortunately, CZ uses 11mm dovetails on some of their rifles, like mine, so this can further complicate mounting as compared to the 3/8 dovetail. I took a gamble and ordered these with the hopes that they would work on my rifle. They went on with little fuss and feel very secure. I had to to very little windage and elevation adjustment on my scope, so this indicates to me that they are on straight. These bases now give me the flexibility of using a variety of Weaver style rings as opposed to the very few and far between 11mm rings.
Pros: Works on 11mm dovetails.
This review was written in the old system and had content requirements that are different than reviews written today.