The NL-50944 is a clear glass nixie tube manufactured by National Electronics. It can display the number 00, 25, 50 and 75, but the digits can't be light up indiviually so there is no possibility in dispalying 55 or 70 for example. This is a very special and odd tube so no information about this tube was found. It is likely that it was used in any system that needed only average decimal precision, like a weight scale to display 1.25 tons, or a cash-register to display 1.25$ or similar. The tube exists in two shapes. If you have any information, I would be happy to hear about it