This special marker is designed for marking in deep holes where a normal pencil is difficult to reach. Ideal for marking on a wide range of materials, except glass. Special features: Suitable for use in deep holes and hard-to-reach places. Writes on almost all surfaces, except glass products. Durable and reliable for various applications. Technical data: Suitable for various materials such as wood, metal, plastic, and concrete. Standard included: 1 deep hole marker.