Step 4: Cut The Tail Off The Plug
The part you have now will fit nicely into the IPhone's recessed jack. There are two problems. First,the "tail" on the back of the plug is functional but hideous and will get snagged on your pockets. If you like ugly stuff, you can leave it alone. Otherwise, trim it down. You want to leave a little in place to add a nicer grip. I used a pair of side cutters to trim the tail but the options are limitless...strong scissors, bolt cutters, tin snips, a hacksaw - pretty much any cutting device you have handy.