Having been away from duplicate since the late 1980's, this book was just what I needed. It really is a comparison of the Standard American bidding system used from 1970 until, at least, the mid or late 1990's.
It outlines, in detail, the many conventional changes and their advantages. Many example hands make it very easy to understand how the various conventions work. The main danger is that you may think the book too
detailed and time consuming to read. This is not a book you read and forget. It becomes a reference text. Incidentally, If your serious about getting in shape, you should also buy Hardy's earlier book on Standard American bidding. The first volume is referred to frequently while reading this book. I'm not a gadget fan and that's not what these books are about. I recommend both the books without reservation. It's funny but I only bought the first book because Mike Lawrence wrote the Forward.