Airmar UST800 Ultrasonic Speed Thru Water and Water Temperature Sensor Provides data for either NMEA 2000 or NMEA 0183 interfaces Simple Plug and Play installation. UST800 designed to replace CS4500 ST800 or ST600 UST800 retrofits into existing Airmar P120 & B120 2" housings UST800 designed to replace CS4500 ST850 or ST650 UST800 retrofits into existing Airmar P17 & B17 2" housings