Plastic 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. Plastic Thru-Hull Transducers require that a hole be drilled in the hull and the shaping of a fairing block. Professional installation is recommended.
Humminbird XPTH-9-HDSI-180-T Plastic Thru Hull Transducer:Dual/High Definition Side Imaging20/74/84 degree200/83/455/800 kHz with built-in temperature30′ cableTransducer dimensions: 5.95″L x 3″WShaft diameter: 1.0″Fairing block included