€¢ 8 oz €¢ Exterior use €¢ Visible after weeks of weather exposure and jobsite wear >> 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 airtight chamber; keeping out moisture and reducing the risk of clumping. Permanent marking chalk is visible after weeks of weather exposure and job site wear; mainly used for exterior.