The Magic Bands

You give a band of paper to two spectators and keep one for yourself. You then ask spectator one and two to cut 2 single bands of paper from the pieces of paper given (by cutting them in half through the centre).
Both try without success, the first cutting one large band and the second cutting two bands linked together. The Magician then shows everyone how do it and takes his well earned bows. Supplied enough for 5 performances.
After you know the secret this is easy to replace. One is made for you. All you need to supply is some glue and some scissors. Very easy to perform.