This arduino Slide Position Sensor is based on straight-slip slide potentiometer sensor. The sensor is able to give provide the position of the slider which is often considered as a linear potentiometer . 

The sensor includes two analog outputs to allow the user to average the values and minimize random sensor fluctuations.  

To ease the difficult of using this sensor,  a Gravity Interface is adapted to allow plug&play.  The IO Sensor Shield is the best match for this sound senor connecting to your .  

A slide potentiometer is commonly seen in music mixer.  

What is potentiometer?

"A potentiometer is an instrument for measuring the potential (voltage) in a circuit. A fraction of a known voltage from a resistive slide wire is compared with an unknown voltage by means of a galvanometer. The sliding contact or wiper of the potentiometer is adjusted and the galvanometer briefly connected between the sliding contact and the unknown voltage. The deflection of the galvanometer is observed and the sliding tap adjusted until the galvanometer no longer deflects from zero. At that point the galvanometer draws no current from the unknown source, and the magnitude of voltage can be calculated from the position of the sliding contact." 

• Voltage: +5 V
  
• Interface Type: Analog
• 5.4kΩ resistance value
• High quality connectors

• Wiki (Analog Slide Position Sensor)
• Schematics

• Analog Slide Position (Potentiometer) Sensor For Arduino x1
• Analog Sensor Cable (SKU:FIT0031) x1