The Napa Service Tools 2835 4" Medium Grit Cylinder Honing Stones are high-quality hand tools designed for automotive use. Made by Napa, a trusted brand in the industry, these honing stones are perfect for smoothing and shaping cylinder walls in engines. With a medium grit size, these stones are durable and effective for various honing applications. The 4" size makes them easy to handle and use, while the manufacturer part number 2835 ensures compatibility with your tools.