The Model V is a glass tube variable-area flow meter that is integrated with the technology of traditional area glass precision and economical brass and stainless steel material. This feature provides accurate medium flow range measurement. It is specially integrated with innovative rotatable scales that are used to read dual air-water direct gradations that show standard cubic feet/minute and standard liter/minute for air. The Model V is also capable of reading GMP and LPM measurements for water. Constructed in a durable and miniature structure, this device is installed in either through vertical in-line or panel mounting. It is designed to measure water flow rates that range from 4 to 20 sL per minute and air flows of 140 to 900 sL per minute.