The Neptune Model 340 Series is a high performance all moulded, dual frequency transducer featuring both high and low frequency sections combined in a single unit. Compatible with a wide range of echo sounders the piston elements are configured to achieve optimum echo sounder performance. The ability to specify a wide combination of frequencies in the same basic unit, provides the echo sounder manufacturer and operator with the flexibility to configure a system and beam pattern to match the desired survey requirements of resolution, range and silt penetration.