A device for manufacturing stacks of product units, in particular of printed products is provided. The pin has an external grooved profile that is engaged by a locking element carried by the box of another riser joint. The computer programmer can employ the code model to locate an object that implements a specific functionality and return a code model object that implements that functionality. The optics may be collimating or non-collimating. A process prepares a polyglycerol composition by reacting glycerol andor a polyglycerol with glycidol in the presence of an activated carbon catalyst. Medicines may also be applied over a large area of skin and during a long period of time to achieve desired treatments.