Just finished a weekend metalworking project using these flap discs, and I'm thoroughly impressed. The zirconia alumina grit bites into metal like a hungry beaver – my angle grinder tore through rust on an old trailer hitch like it was butter. What surprised me most? After three hours of aggressive grinding, the 60-grit disc still had plenty of life left.

The fiberglass backing makes a noticeable difference when you're working overhead. Unlike cheaper discs that make your hands tingle from vibration, these stay remarkably stable even at max RPM. I did notice the flaps are slightly thinner than premium brands (as another reviewer mentioned), but honestly? For how I use them – mostly until they clog with material – it hasn't affected performance one bit.

Where these really shine is value. Used the 120-grit to blend welds on a steel gate, and the finish was shockingly smooth for budget discs. Pro tip: Keep a wire brush handy to occasionally clean out the flaps when working with soft metals – extends their life dramatically.

Would I use these in a professional shop running grinders 8 hours daily? Probably not. But for weekend warriors tackling garage projects or farm repairs? Absolute gold mine. Already ordered another set before my current discs wear out – that's how much I believe in them.