Raymarine B258 Through Hull Transducer

Bronze, 1kW, Dual Frequency (50/200 kHz) for CP370 Sonar

B258 Overview
The B258 features 4 internal ceramics for increased sensitivity and better deep water performance. The included fairing block ensures uninterrupted performance, even at speed.
The B258 is 25 times more sensitive than a single-element 50/200 kHz transducer. This innovative 1 kW transducer makes 600 W fishfinders perform like their more powerful big brothers — especially at 50 kHz. How does it do it? The B258 uses a high-performance ceramic-element construction. The resulting narrow beams will clearly distinguish individual fish and bottom fish from their habitat at depths down to 670 m (2,200’). 
Included with the B258 is a custom fit, high-performance fairing block.  When installed properly, this transducer is capable of clear images and a clean bottom trace at speeds over 30 knots (34 MPH).