Compatible with the following instruments: ST70 (direct connect to ST70 backbone, no pod required. Hole diameter for installation: 2 inch. Operates at 235kHz so there is no interference with your 50 to200 kHz fish finder transducer. Airmar Smart Sensors have embedded microelectronics, meaning the signal is processed from within the transducer itself, eliminating the need for an ST70 transducer pod. Depth and Temperature.