Indasa 4.5" Rhynofibre "A" Silver Resin Fiber Grinding Discs (4500 Series) are a premium abrasive featuring aluminum oxide mineral grain, durable vulcanized backing, high strength resin to eliminate shredding and high initial cutting action. Excellent quality - offers high initial cut, better heat resistance, better edge stability and last far longer than low quality discs flooding the market. Perfect for machine grinding and sanding of metal work and fiberglass. Sold 25 discs per box. Indasa Rhynofibre discs are also available in 5" and 7" sizes and in many grit options.