ALIGN PILATES MATTRESS CONVERTER for C SERIES Pilates Reformers, ,Extend your reformer with the addition of the mattress converter for your Align-Pilates C* Series Reformer, which must be used in conjunction with the Platform Extender (available here), to convert your C Series Pilates reformer into a completely flat bed. The fully flat bed can be used in conjunction with the A2 wall mounted half cadillac to add additional repertoire.