This is a well-made part of the costume - and the one that will garner the most "oohs" and "ahhs". The response is always, "I was wondering if you were going to have the retractible knife!" As Thomas mentioned, it is not spring-loaded, presumable for liability reasons. However, when posing for photo shots, it is easy and quick enough to extend the blade without them really noticing you did it. Generally, you will be wearing it higher on the forearm than shown, but the piece will still interfere slightly with coordination due to the metal extending into the base of the palm and also due to impeding the wrist from bending. (The hardest thing I had with it was retrieving my cell phone from its holder on the back of my belt covered my the cape.) However, this is not a serious issue at all. The brace could use one more strip of snaps for those who aren't Popeye.