The 153D-20-40-1 Smart Exhaust Throttle Valve with Integrated Controller features a 0.779 in. (20 mm) nominal inside diameter and a size NW40 ISO-KF flange. A flapper O-ring is included. The 153D "Smart" Exhaust Throttle Valve integrates all control, communication, and driver circuits via a compact "add-on" electronics module within a 253 Throttle Valve assembly, eliminating the need for a separate pressure control electronics module. The 153 is operable in two modes, flapper positioning or pressure control.