4010P Tecmark 4000 Series pressure switch is a 25 amp, SPNO and 2 terminal. The thread is 1/8" NPT which is the standard used. This pressure switch is a great replacement for most 25amp pressure switches, and due to its non-metal structure will not oxidize or rust. It is perfect for salt water & high moisture areas. The 4010p can also be used as a replacement for the 3029 & 3029p.