Type DT-574 hydrophone that was once used in the bow mounted spherical array of the BQQ-6 sonar aboard US nuclear missile submarines. It uses piezoelectric ceramic elements that are encased in polyethylene and connected to a polyethylene insulated 2 conductor cable (1PR-20). It has 3 metal inserts that are used for mounting with bolts in the array (the inserts prevent the bolts from deforming the polyethylene). Dimensions are 3 inches in diameter X 2 inches high. This hydrophone was never used and is in new condition although with only a 5 inch long cable.