Package contents: 5 boxes of red universal pencil refills. Material and cleanup: The refills use a fire-extinguishing weak material; they are water-soluble and can be wiped clean with a damp cloth. Pencil case: The included pencil case protects pencil leads from dust, liquids and rust, helping keep construction work neat and efficient. Size: 12 cm (4.72 inches) long, diameter 2.8 mm (0.07 inches). Compatibility and performance: Standard replacement parts for Chinese construction pens on the market. Designed for reliable fit and consistent marking in professional settings. Applications and use scenarios: - Carpenters: mark precise cut lines on wood or panels during fabrication. - Tilers: lay out tile grid and alignment marks before installation. - Architects, engineers, and decoration workers: on-site reference marks for accurate placement and layout during construction or renovation projects.