They work, but there are better.
I have had a set of these for 7 months. The pros are a longer wire than BD's and the curved shape fits bulges well. The cons are that the smallest BD#5 equivalent is only rated to 4kN and the BD is 6kN, the curved shape doesn't work in uniform constrictions as well as the BD nuts and there are some gaps in the size range. For what you get I would recommend the BD Stoppers or the DMM Wallnuts over these. That being said, nuts are pretty simple and these would still hold a fall if placed correctly.