The TR-330A /AN/SQS-56 sonar transducer is used in surface ship applications and features a low operating frequency band ranging from 6 kHz to 9 kHz.

The modular construction of the transducer facilitates assembly into multiple element arrays, in any desired configuration, to achieve the beam pattern and source level required.
A complete array is comprised of 288 transducer elements, 36 stave assemblies, and 36 cable assemblies.

A variant of the TR-330A features a GRE (Glass Reinforced Epoxy) connector, with a double "O" ring seal available as an option.