Designed to turn a lathe into a cylindrical grinder, the Duplex is a high-quality product and available in a wide range of sizes and types--including special one-offs and modified standard units. All spindles ran in high-precision ball or roller races and all models could be had with a single or three-phase motor and in  either a left-hand-or right-hand fitting.
The range shown below covers most of the types offered and, as all work in much the same way, the operating manual will certainly help get the best from all by this maker.
The Company is now known as Jena Duplex and design, manufacture, supply, servicing and repair of linear and rotary motion products and machine parts. A late version of their toolpost grinder catalogue, issued in 2005, can be downloaded here.