Cathe Friedrichs STS (Shock Training System) is a 36-DVD set of strength training routines to be completed over a period of 3-1/2 months. It is for advanced exercisers, and it is intense! It requires you to have a barbell, various dumbbells, a step or weight bench, and an exercise band (like a Dyna-band). There are 3 workouts per week, about one hour each. You are supposed to supplement this all-strength program with cardio on three other days per week. This is the most comprehensive, professional, advanced, high-quality at-home exercise system that I have ever done. I have done P90X, and it simply does not compare to STS, either in variety or level of challenge. STS blows it away in every category. Cathe Friedrichs is a consummate professional and, I suspect, a real perfectionist, because for years she has been putting out the highest quality home exercise videos/DVD's on the market. STS is no exception. It's also not for beginners.