A B-scan is an image showing a cross-sectional profile through one vertical slice of the test piece, showing the depth of reflectors with respect to their linear position. B-scan imaging requires that the sound beam be scanned along the selected axis of the test piece, either mechanically or electronically, while storing relevant data. In the case below, the B-scan shows two deep reflectors and one shallower reflector, corresponding to the positions of the side drilled holes in the test block. With a conventional flaw detector, the transducer must be moved laterally across the test piece.