The Yokogawa AEA4D is a Rotameter, also known as a variable area flowmeter. It is designed for direct, visual indication of flow rates for liquids and gases in small to medium pipeline sizes. This model is characterized by its metal tube construction and flanged connection, making it suitable for higher pressure and temperature applications compared to glass tube rotameters. It provides a cost-effective and reliable solution for flow monitoring in various industrial processes where a local indicator is sufficient.