A lot of people hate these rings. Personally, I think they're not bad, and well worth their low price. The little clamps look as though they wouldn't be strong, but I had a pair on a Sako in .375 H&H (they make a set for the Sako dovetail, basically their standard ring design but using an intermediate piece between ring and receiver) and they held for several years and many hundreds of rounds without problems. They give you a slight but useable amount of windage correction in both front and rear positions, and they aren't totally hideous. The rimfire version is nice because it works with some of the imported dovetails that are slightly larger than standard 3/8-inch.
Not saying I love'em...I don't...but there are much worse rings out there.