At first glance, the Contrology Reformer Springs all look the same. The "body" of the springs (the twisted, spiral part), the width and the length look almost identical. The big difference lies in the hooks. The standard Contrology reformer spring has a shorter open hook at one end and a longer "long neck" hook at the other end. The "long neck" hook extends the overall length of the spring by about 25 mm. The "long neck" hook on the standard Contrology reformer spring provides a certain smoothness when the carriage starts to move and returns to its starting position.

Work was done with Kathi Ross-Nash on the New York Pilates Reformer Springs to replicate the original springs she used in her training with Romana. The New York Pilates Reformer Springs have shorter hooks at both ends. The shorter hooks ensure that the transition from taut springs to loose springs is quicker, resulting in a subtle but distinctive feel. The Contrology Reformers have a spring holder attached to the carriage, which needs to be adjusted for the New York Pilates Reformer Springs.