[Harry grunts, annoyed and frustrated. Sylphs are never easy to deal with. He'd love to just hex the thing, but there are people around and that'd be a bad idea.]

Iron. If I can catch the sylph with some, it should knock it out long enough for me to banish it back to the Nevernever. [He fights to open the screw top of the jar.] Of course it gets stuck when I finally get a shot at the faerie.