They are also used to dry out your flies when you are finished fishing. A good fly box can save you hundreds of dollars in flies. Dry fly floatants are silicone based. Gink is used to assist your dry flies in floating. Fisherman use Zink at times to help let your leader sink below the surface.
Leader are light lengths of monofilament that connect the fly to the fly line.
Fisherman should carry a few different size and length leaders while on the river. Hemostats are essential for removing a fly from the fish's mouth without hurting the fish and destroying your fly. They are available in both curved and straight designs. A good pair of scissors is something to carry for trimming flies and for cutting back leaders. You can't drive a hook that is dull.