Airmar P17 plastic thru-hull housing.
New, never installed, in original sealed bags.
P17 housing w/ o-ring and nut.
Originally came w/ B&G sensors but viable as a housing for Airmar sensors listed below.
Fits: Airmar P17 Depth Insert, ST550, ST650, ST850, UST850, UDST800 and Smart Sensors. 2-12 Thread