These tungsten heads are very heavy and will sink your flies even in fast current. Head is shaped like minnow head.
You can attach the head to the when the fly is finished. Just add small amount of glue behind hook eye and attach the head. Leave 1-2 mm empty between head and hook eye so the fly is easier to tie to the leader.
Works with normal straight and down eye streamer hooks. Heads contain eyes for giving final touch to your flies.
See the table below for package sizes, head weights and hook recommendation in different sizes:
||#8 - 6
||#1 - 6/0
||#6 - 2