Bronze Thru Hull TransducerBronze Thru-Hull Transducers are for large boats and for boats with in-board motors that make typical Transom Mount Transducers ineffective. They are not recommended for trailered boats as the transducer is not flush with the hull. Bronze Thru-Hull Transducers require that a hole be drilled in the hull and the shaping of a fairing block. Professional installation is recommended. Plastic Thru-Hull Transducers are an alternative to Bronze Thru-Hull Transducers.Description: Bronze thru hull transducer, single or dual beam use. 20/60 degree, 200/83kHz. Transducer dimensions: 5.25L X 2.75W X 1.2D below hull Shaft diameter: .86. Fairing block not included.