Why would you use equipment for Pilates?
Exercises with special Pilates equipment offer more resistance and more types of exercise for the arms and legs (especially the upper body) than matwork exercises. But abdominal exercises in matwork Pilates are usually harder than the machine-based because the equipment supports the legs during exercises that involve leg raises. By mixing matwork and machine Pilates, you get a more total muscle-strengthening program.
The principle piece of Pilates equipment is the Reformer. The other important equipment are the Cadillac, Chair and Ladder Barrel.