They're alright, and get the job done. You need to cut some strings? These will do it. BUT - they are not as strong as described.
In the description it said that it can cut the deep B-string on bass "easily", but it takes some force to actually do it.
It's not perfect on thinner strings either. After cutting even guitar strings, I still had to jiggle/move the cutter around a bit, for the two string-pieces to separate. But as mentioned, it will definitely cut through the strings, just not as well as other string cutters