If it's made by Walter there are two things you can count on 1) It's not going to be cheap. 2) It will work as well as any product in it's category or better.
I call it the 3M method of doing business. Pay up, but it works.
When they start wearing down spin it and hold a file or something similar and knock off the ribs on the back side. You will get longer life.
I have been using them for quite a few years because they were standard supply on our job sites but in the last couple years they have been switching to fibre discs.