APPARATUS 6 - USP The Apparatus 6 Rotating Cylinder is used for testing Transdermal Patches in any standard Dissolution Test Station. The cylinder is available in 2 size, for small and large patches. All cylinders are made of 316 stainless steel, are electropolished and are serialized for identification/tractability purposes. All cylinders are equivalents of original OEMs. Is there something you can't find, please feel free to contact us for custom work.