This is the top selling T'ai Chi video series in the world, written by and featuring Bill Douglas, founder of World T'ai Chi Day. This design has seen several format changes. Originally an audio cassette series, it was later redone as a series of videos. The next design change came when the series was released on DVD. When the DVD was later released in several foreign countries, the box had to be reformatted again because the standard DVD box is different in different parts of the world. I'm going to get a head start by working now on the micro-chip release, which is probably just around the corner.