The STANDARD size Reformer Box is for use with all Stott Pilates Reformer models and is the standard studio size; The EXTRA-TALL size is often used with a lower carriage height like the STOTT PILATES SPX Reformer series; The EXTRA-LONG size is used often with extended length Reformers
The additional height of the Reformer Box allows greater range of motion and facilitates a variety of exercises while seated or lying on the Reformer