Real world
Hand brake wheels, crampons, anchors, brake switches and document boxes - these are all essential parts of every cargo wagon (except for the brake switches, which are also present on coaches), even when they are often hard to see. Hand brake wheel does the same job as the hand brake in your car, crampons are used by rail staff during wagons shifting, anchors are used quite rarely nowadays for towing wagons by ropes when a locomotive cannot be used or is not available, brake switches adjust braking behavior (mainly the applied pressure) and the document boxes serve to store shipping documents.
Model
Use this only if you are a very experienced modeler, since the individual parts are tiny and VERY brittle, so you can easily lost them or break them. It is strongly recommended to paint the individual parts first, because they are very hard to handle after they got removed from the plate. DO NOT break off the parts from the plate. Insted use a sharp blade (safety first!) to cut them off and polish the parts after the incision. Use super glue to attach parts to a wagon. Photos of real world vehicles will help you to position them properly. This accessories can be used with literally any cargo wagon that is run in Europe.
Technical specifications