This is perfect if you do any needle through arm tricks. Another good one is Pain by Paul Harris in his Art of Astonishment book. Even if you don't use it for magic you'll find other reasons to use it too. It's pretty easy to make your own fake blood but the professional stuff will look better. If you love pulling pranks, pick some up.

I love this stuff. You get a bottle with A LOT of fake blood inside and it really looks like real blood. I faked a nose bleed and everyone thought it was really even when they looked up real close! Awesome stuff

This is the best stage blood I've ever used... and it's perfect for more than just the needle thru arm trick... the reason I gave it a 4 was because it stain's your fingers and that sometimes gives the trick away.