The CRESCENT NICHOLSON® half round double cut bastard files are ideal for materials containing iron, mild steel, plastics and wood. The coarse grade is perfect for use on concave, convex and flat surfaces. The two sided files are rounded on 1 side and flat on the other, so you can round out holes with ease. Half round bastard files are double cut on the rounded sides, allowing you to quickly remove material from the work piece.