Merlins of Wakefield - It's always magic at Merlins

A NEW WONDERFUL IDEA IN ROPE MAGIC!
You show an elegant velvet bag with three coloured ropes dangling from it. You say that one rope is different from the others (colours aside). A spectator FREELY (and we mean FREELY) selects one rope and HE removes the other two from the bag. They do not have a knot. He then removes the third rope and it is seen to have a knot (and the spectator can UNTIE it!). Comes complete with ropes, bag, and detailed instructions for performing this awesome effect!