The Reformer is the most popular Pilates apparatus designed by Joseph Pilates. It consists of a carriage that moves back and forth along tracks within a frame. The resistance is provided by the exerciser’s body weight and by the Pilates secret sauce – a set of springs attached to both the carriage and the platform. The Reformer apparatus functions primarily as a resistance device forcing the user to work precisely within its grid. This promotes the development of good alignment, core strength, and flexibility.