- Spectra Symbol created the breakthrough form-factor of Membrane Sensor Technology, with 0.5 mm height, and has revolutionized how OEMs can use full-travel position feedback. These inexpensive full-travel sensors range from 12.5 mm to 1,000 mm in stock. Included in the Spectra Symbol product line are the Flex Sensor, medical-grade SoftPot, narrow ThinPot, high temp. HotPot and contactless MagnetoPot Sensors.