The GR-201 is a medium-sized top-view nixie tube made by the company Rodan-Okaya. It is an early version of the CD-11, which evolved over time – there are at least six variants, shown at the end of the gallery. Apart from the labelling, they vary by the shape of the anode grid and the support structures.
Here are some photographs of the tube from various angles, followed by a video of it in action. The datasheet is at the end.