Tri Clamp concentric reducers decrease in diameter towards the center this forming a conical cylinder. A concentric reducer is often used inline on a vertical flow application, or if laid horizontally, as an increaser. We do not recommend reducing in the horizontal as pooling may occur. In these cases, an eccentric reducer, which lays flat on one side is preferable. Concentric reducers have a lower chance of producing agitation like an end cap reducer may, NPT/NPS pipe size interior diamter (ID).