OWL FO-4B Bold Fiber OWL 4 Optical Power Meter is a highly accuracy, high resolution microprocessor controlled optical power meter with a 75dB dynamic range. Features an integrated light source (ST connector port standard) making optical length measurement a breeze. The OWL FO 4B Bold Fiber OWL 4 Optical Power Meter has a large backlit LCD display and a 2.5mm universal adapter port.