The ST800 speed and temperature sensor processes a digital signal inside the housing. Then this Speed Sensor sends the data to a chart plotter, radar screen, depth Display in analogue format. The plastic P120 housing is included. These low-profile units are nearly flush and minimize drag with only 5 mm (3/16") extending outside of the hull.
Features
Speed and temperature sensor only.
Compatible hull material: aluminium and fiberglass
Cable 14m (45ft) cable with connector
iso spade connectors 
Retractable plastic with valve sleeve
ST800—Retrofits into Airmar P120 and B120 housings
Speed Range: 2 knots to 45 knots (2 MPH to 52 MPH)
Compatible Models
ST40
i40
ST60
ST60+
i50
ST70 via Pod
i70 via iTC-5