I must have the toughest arm hair on the planet. I've tried everything from files, stones, ceramics, to the Muzzy carbide sharpener to get these heads sharp and nothing seems to work. I've used medium to very light pressure to where I almost put myself in a trance and still can't get a hunting edge. I can shave hair with my Gerber knife after using the Muzzy sharpener on it, but not the Phantoms. I'm gettin really frustrated with these heads so any suggestions would be muchly appreciated. Thanks and God Bless, Steve