Irwin Strait-Line Red Permanent Chalk Line Chalk, 2-1/2 lb. is designed specifically for use with reel type chalkline boxes, making it an essential tool for precision marking on your jobsite. This chalk is conveniently packaged in a plastic squeeze bottle with a fast fill spout for easy application and quick refills. I for exterior use, it works effectively on a variety of surfaces including wood, drywall, concrete, stone, and metal. The permanent red color ensures long-lasting, highly visible lines that resist fading even after weeks of exposure to weather and typical jobsite wear. This chalk a permanence rating of 3 on a scale of 0 to 4, providing reliable durability and visibility for your projects. Model Number: 65202