It's a downloadable cardio instruction series. You can download on to an IPOD or MP3 player or you can buy on a CD. You listen to the instructor and follow the different steps and challenges, ie: warmup, hill climb, sprint etc. Sean, the instructor's voice is very easy to listen to and the background music is very motivational. You can hear samples at cardiocoach.com. You can use them on just about any cardio equipment.