The fibre identifiers, used for identifying the light power presence in optical fibres, include three detecting functions: TONE, TRAFFIC, and ONU. Both models include a trigger operated clamp to macro-bend the fibre in order to leak light which is then detected by two photo sensors. The fibre identifiers can detect the presence of several kinds of light signal and indicate signal directions. The trigger lock function ensures the fibre is clamped with constant pressure, while the 2.4" colour LCD touch panel, equipped with a backlight function, allows the user to view the estimated optical power in the fibre and select the desired wavelength of 1310nm, 1490nm, or 1550nm. Identification of modulated tones at 270Hz, 1kHz and 2kHz is provided, along with continuous wave and ONU signals. Users are also able to select from three detection sensitivity modes; normal, fast and fine. Other features of the battery operated FID30R/FID31R include robust body design, easy-to-use fibre clamp, status indicator and adjustable settings for result retaining, buzzer volume, backlight brightness, auto dimming and auto power off. The fibre identifiers can be used for UV-coated fibre, 0.9mm diameter tight buffered fibre, fibre cord up to 3mm in diameter, and fibre ribbon with up to 12 fibres.