Applications: Marking on metal, glass, plastic, rubber, and wood. [Functions and Features] It does not fray even if you write quickly, and it can be written on a variety of materials. Made with a PET fiber core that writes soft and does not produce annoying noise. Non-slip rubber grip. Strap hook prevents rolling Material: Shaft: Recycled PP resin. Pen core (thick): PET resin. Pen core (fine): acrylic fiber. Mitsubishi Pencil Co., Ltd. Black permanent marker pieces are sold online by DCM Online. We also carry many other carpentry tools.