The FT152 retain sensor is a bottom retain detection sensor. The sensor has a 1/2" NPT mounting. Sensor is shipped with a 1/2" NPT weld-on aluminum half coupling for mounting. The main sensor portion is stainless steel to prevent galling in the trailer. The wiring box is plastic to prevent corrosion and is removable to facilitate installation. The side ports come out of the same side (like the overfill sensors) to make wiring easier. The FT152 is mechanically and electrically compatible with Scully model 08819 and the Scully Intellicheck System. Our new three port housing design is compatible with previous inline and parallel dual port housings.