If this is what your are refering to,(Disregard the blue Mustard hook box) I have used them but don't find them to be all that great for fly fishing. As already been mentioned they are ok for 'med' flys but don't work for small ones <14/16. I find that the eye is either to big (thickness of eye) or too small (eye too small to fit on snap). This of course depends on what brand of hooks you use. In addition when using light tippets trying to snap a hook/fly on to these things will break your tippets. I have also found that the jaws of the snaps will open up with use and you will lose flies.