Specifications: Blackened cleanliness that wont easily fall off even when rubbed. Can be used to write on a variety of things. Material: Shaft: Recycled PP, Pen Core: Fiber Bundles (Acrylic); Body Size: Shaft Diameter 0.4 x Total Length 5.5 inches (10.7 x 139.1 mm); Product Weight: 0.3 oz (8.1 g); Writing Line Width: 0.04 inches (0.9 mm); Oil-based and fine round core.