The Rodan MG-19B is a small segmented nixie display, likely intended for use in calculators. Produced in Japan, the MG-19B was sold under the Elfin trade name in the US. The tube's most noteworthy feature is the inclusion of two additional diagonal segment in the middle of the tube, which allows for the display of a more pleasing '7' character as well as several additional alphanumeric symbols. Each of the diagonal segments is brought out to a separate pin on the base, allowing them to be controlled individually. Digit height on this tube is 11mm and the entire envelope is 49mm long including the nipple. Unlike it's close neon display relative, the MG-17F, the MG-19B has only a single lower decimal point, which makes the tube a poor choice for inverse mounting.
The example shown here is an Alco branded variant of this tube. The MG-19B appears to have been sold by several different manufacturers.