The IN-18 clear glass numeric nixie tube made by Reflector / Sovtek. With 40mm symbold height, it is the biggest russian nixie. This tube is perfect for projects where a big digit is needed, but those tube became more and more expensive. In March 2016, ebay prices for the IN-18 are around 50$ per tube. The next bigger tubes (Z568M, 50mm) are usually about 200. Sadly, there are alot of "used" IN-18 tubes for sale, which will have small defects