I remember buying this booklet at Tannen's Magic in NYC, over 15 years ago. It's a pretty anonymous looking text, but the salesman at Tannen's gave this inexpensive item a high, solid pitch-this considering that he COULD have pitched me some pricier props/tricks. After years, I STILL use Kozlowski's version of the switch. I practiced it religiously until I could do it in my sleep. I emphasize practice, but it is so well worth it. It took me several weeks to get it down smooth. Like learning the coin roll: the more you do it, the more possible it becomes-(unlike in the beginning, where you might think 'how can my hands do THAT?!!')
I have other versions of bill changes, including Camirand's 'Dynaswitch'. Very visual and magical. I still prefer THIS version, because it is so clean. For the guilt to be so INVISIBLE yet mere INCHES from the spectator's eyes, is a testimony to this method-and also to a classic device we all use. I sometimes do a mismade bill effect instead of one to a hundred, but whichever, I do it INCHES from the spectator. There are NO telltale extra bill flaps, the handling shows your hands free and 'CLEAN', before AND after-and the folding/unfolding sequence when done properly, keeps the bill(s) in constant view.
Two things I kept clear with this effect. One, is that I don't use a borrowed bill, although I could-the second, is finding the right 'something' to use for this effect. We all have several of them already. The 'something' is usually not handled the way it is here, and it must have enough surface 'traction' or texture to stay in place when you need it to. A bit of sandpaper rubbed on the 'something' works fine. If you use this bill switch method, you will be greatly rewarded by the effort involved. For me, it was learning a technique/trick, but more, it challenged my sense of commitment and dedication. This book/method is still around because it WORKS LIKE MAGIC.