The Arcay top dust is a hydrophobic (water-repellent) powder that can be used to revitalise and re-float any dry fly after it becomes waterlogged through prolonged use or after a fish capture.
Whilst suitable for all dry fly patterns, it is especially valuable when using CDC flies.
The top dust container is great for those who like to use their fingers to pick some powder and then treat the fly, rather than using a brush.