FEA100 insertion flowmeters are an economic alternative to full bore flowmeters. They comprise an electromagnetic sensing head mounted on the end of a support rod. FEA100 finds application in existing water distribution systems where provision for flow metering was not originally made and where a full bore flow meter would be uneconomic. The assembly can be installed in existing pipelines without the need for major excavations or alterations to pipe work normally associated with the installation full bore meters.