CHALK REFILL POWDERED 5LB. BLUE. This product is a Keson brand marking chalk refill that can be used on chalk line spools to produce water and weather resistant semi-permanent lines that stick and bump for a long time but eventually wear out. The product can provide up to 5 yield line strokes, plus large flow to make coil filling much easier. Its outdoor applications include, in other things, roofing, concrete layouts and metal fabrication.