The Crescent Nicholson half-round double-cut bastard files are ideal for materials containing iron, mild steel, plastics and wood. The coarse grade is ideal for use on concave, convex and flat surfaces. The two-sided files are rounded on one 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.