[jester316]

What type of m16 do you have? Does it have rails on the hand guard? If it does, ONLY the second one will work. If you don't have rails, ONLY the first one will work. They are only different in the way they attach to your rifle. If you need the first one, I would get this set. That would look much better than just the 203 hanging there with a regular hand guard on top.