Irwin STRAIT-LINE Marking chalks have a newly engineered flip-top cap that keeps the chalk in the bottle where you want it and stops it from spilling out in areas that you don’t. The flip-top cap, available on all Irwin STRAIT-LINE chalk bottles, seals the chalk in an air-tight chamber, keeping out moisture and reducing the risk of clumping.

• Exterior use
• Ideal for low light conditions and on dark surfaces
• Use to show layout changes and corrections