Just finished testing these 36-grit zirconia sanding discs on multiple projects, and here's the real deal: they're the unsung heroes of my workshop. The resin fiber backing holds up surprisingly well during aggressive metal grinding sessions - I removed years of rust from old garden tools without a single disc tearing.

The flexibility surprised me most. Without a backing pad (like when I was contouring wooden chair legs), they conform beautifully to curved surfaces. But pro tip: always use the included 7/8'' arbor with a backing pad for serious material removal - it transforms your angle grinder into a terrifyingly effective sander.

Durability is hit-or-miss. While grinding concrete residue off bricks, I burned through three discs in 20 minutes. Yet when deburring aluminum sheets later, one disc lasted through the entire project. The lack of grit markings is annoying - I nearly ruined a delicate wood carving by accidentally grabbing one of these beasts instead of my finer grit discs.

Where these shine? Value. At less than $1 per disc, I don't feel guilty abusing them on nasty jobs like removing boat hull paint or shaping forged steel. They're not premium quality, but for weekend warriors tackling varied projects, this 25-pack offers incredible versatility at hardware-store prices.