The gripping ring, a protruding edge on the side of the dish greatly simplifies the delicate separation of the upper and lower parts. Of great significance is the ease and security of stacking. When several dishes are stacked up, viewing is possible using transmitted light. Their transportation from A to B is simple and secure by means of the gripping ring. The cams on the inside of the dish lid maintain a gap between lid and dish to ensure a constant movement of air in the closed condition and limit condensation. An improved surface treatment of the growth zone ensures constant results | 
