QUANTITY: This listing is for a pack of fifty (50) pieces of our 4-1/2" cutting wheels. DIMENSIONS: Each disc is four and a half (4.5) inches in diameter with a 7/8" metal center and .040" thickness. These are Type 1 (flat) discs. USE: These cutoff wheels are designed for cutting fiberglass, steel, iron, plastic, stainless steel, and other ferrous metals.