Tecmark Pressure Switch [3903-DF Adj SPST] (3903-DF) aquasun or worn beyond service use

or worn beyond service use

Complete jet for compatible Balboa slimline applications

Blue solar finish

The 3/8 inch cross-section gives this O-ring practical value because very large assemblies often require significantly more sealing mass than standard profiles can provide

When a topside panel becomes unreadable

Tecmark Pressure Switch [3903-DF Adj SPST] (3903-DF) aquasun or worn beyond service useTecmark Pressure Switch [3903 DF Adj SPST] (3903 DF) is a Tecmark replacement pressure switch used in compatible spa and hot tub control systems. Pressure switches help monitor water flow or pressure conditions so equipment can operate with the intended safety logic and control response. A failing or mismatched pressure switch can contribute to heating errors, equipment interruptions, or unreliable system operation. This replacement is intended for