I always carry on my key chain a BSA Hot Spark metal alloy rod, a poker chip shaped thing that has a piece of steel imbedded in it (I use steel for striker and for knife sharpening), a whistle, and a pill fob that has 3 "spark-lite" tinders in it. My work has me in remote areas sometimes and this is minimal, along with my pocket knife, incase I get stranded.

Anyway, I have flown several times with this keychain (the knife goes in checked luggage but I do carry scissors in my carry-on) and have never had TSA take a second look at the keychain.