Mineral salts pyridone broth is a selective medium for bacteria that can metabolizepyridone[?] (which is an unusual carbon source that only a select few types of bacteria can use). This medium is used to isolate bacteria belonging to the Arthrobacter genus among other bacteria genera.
... spinning mass and it rests in a little groove inside the wrist exerciser device, which almost completely covers the gyroscope inside it, except for a small round opening ...