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" Operates at 235kHz so there is no interference with your 50/200 kHz fishfinder transducer. Airmar's 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