These were the first bits of pro I ever purchased. I bought the 1-13 set when I was starting out and they are very solid. Personally I prefer the ease of placing and cleaning cams, but everyone needs a set of stoppers, and when set right stoppers are super strong placements and yet so lightweight. I don't really see much difference in these stoppers compared to most others of the similar shape and material. I find the useful range of these stoppers to be 4-13, though I really don't prefer placing anything lower than 9 because 9-13 have the opening, and I find I can remove these with my nut tool easier. I have had to clean these even after being weighted, and I've always been able to remove these without having to damage the rock or the nut. The color coding is helpful. A quick note according to the tech specs on this page it says "7/8 2kN", this is obviously meant to be 1/2 not 7/8.