The GR-211 is a large Nixie tube produced by Rodan-Okaya in Japan. It ranks as the third-largest Nixie tube made by Rodan and succeeded the short-lived GR-11. Later models were rebranded as CD94. Notably, the GR-211 includes a left decimal point, which is uncommon for tubes of its size. In devices using larger Nixie tubes, a separate neon bulb typically represented the comma instead. Interestingly, the datasheet marks the decimal point’s pin as “not connected.”

The MG-19B is a tiny, segmented neon-filled display tube produced by Rodan and marketed under the Elfin brand, designed for use in small electronic instruments. It features two additional diagonal segments, enabling it to display the digits ‘1’ and ‘7’ more naturally, as well as certain other alphanumeric characters. The tube also includes a right decimal point. Unlike Nixie tubes, each cathode in the MG-19B requires an individual resistor, as the current needed varies with the number of illuminated segments. With a 180V breakdown voltage and a recommended 230V anode voltage, the tube operates at significantly higher voltages than most Nixie tubes. This made driving the MG-19B more complex, as affordable high-voltage transistors were not readily available when the tube was introduced.