The AQ7255 single-mode fiber optical unit (wavelength: 1.31/15.5 Microm) provides a dynamic range of 41.5/39.5 dB. In addition, the short dead zone of the instrument detects reflections occurring as close as three meters. Improvements in measuring speed enable the AQ7250 to measure a splice loss of 0.5 dB produced 70km away-- in 20 seconds.