With the bleed plug completely removed, the open bleed fitting provides a port through which one may apply air pressure for testing the response of the pressure transmitter. A special test fitting called a bleed port adapter – colloquially known as a stinger – threads into the opened bleed fitting to connect a hand-held air pump and test pressure gauge to the transmitter, conveniently allowing the transmitter to be tested without un-doing any of the manifold bolts, tapered thread pipe connections, or impulse tube compression fittings. When performing field checks of pressure transmitters, bleed port adapters substantially reduce the amount of time necessary to test each instrument.