Abstract: A flexible tape is releasably wound into a coil within a housing. Optically sensed encoded markings along the length of the tape are illuminated by a light source through fiber optic bundles. The light reflected from the illuminated markings is transmitted by additional fiber optic bundles to two light detectors for sensing the markings as the tape is wound or unwound from the coil. The markings are counted as they pass the fiber optic bundles by electronic logic circuitry the output of which controls a digital display on the housing.Two sets of markings are provided along the tape so that the display may be switched between metric and feet and inch units without making substantial changes in the electronic logic circuitry. The electronic count may be reset to zero at any extension of the tape and subsequent readings would then be plus or minus from that extension.