€¢ For interior and exterior use €¢ Marks are temporary €¢ Provides great visibility >> 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(r) chalk bottles; seals the chalk in an air-tight chamber; keeping out moisture and reducing the risk of clumping. Micro-fine for more marking power; interior or exterior use. Marks are temporary and provides great visibility.