This antenna has an interface probe attached to suit Elster V100 style water meters (20mm to 40mm types). This enables the AT301 to receive the water meter signal data and display the consumption and cost on the Control Panel in almost real time with a 10 minute delay. This 3 metre extended antenna can be used if the Control Unit is placed underground or in a shielded location where the radio signal cannot be easily read by the Control Panel. The extension can then be used to relocate the antenna to a point where the signal is accessible. If the Control Unit is not shielded, use the Short antenna version of the water meter connection. Part # ANT2-0B.