I love em, as solid as you can get and not expensive, I always lap them, top and bottom. Some people just lap the bottom. They hold the Night Forces on my 50bmg and .308 and everything else in 1". They do not make a 35mm set so I had to buy Valadia or V-Tac for the 338 RUM. They are steel and nice rings ,but only 4-ring screws and not nearly as wide. I like the wider profile, even though I lap and Rosin the rings, it only makes since the a wider bearing surface would hold it better.