Digital Multilayer Disk (DMD) is an optical disc format developed by D Data Inc. It is based on the 3D optical data storage technology developed for the Fluorescent Multilayer Disc by the defunct company Constellation 3D. DMD discs can store between 22 and 32 GB of binary information. It is based on red laser technology, so DMD discs and players can be easily made in existing production facilities with little modifications. Discs are composed of multiple data layers joined by a fluorescent material. Unlike DVDs and CDs, DMD do not have metallic layers, so they are nearly transparent. DMDs are coated with proprietary chemical compositions, and those chemicals react when the red laser shines on a particular layer. The chemical reaction then generates a signal, which is then read by the disc reader. This allows for discs to potentially have up to 100 GB of storage space.