Compatible with the following instruments: ST70 direct connect to ST70 backbone, no pod required. Compatible hull material: aluminum and fiberglass. Hole diameter for installation: 2 inches. Operates at 235kHz so there is no interference with your 50 to 200 kHz fish finder transducer. Air mar Smart Sensors have embedded microelectronics, meaning the signal is processed from within the transducer itself, eliminating the need for an ST70 transducer pod. Depth, Speedáand Temperature.