This is a small Force Sensitive Resistor . It has an Active Detection Area of 0.16 "(4mm) in Diameter. This FSR from Interlink Electronics varies its Resistance depending on how much Pressure is being applied to the Detection Area. The stronger the Force, the lower the Resistance. When there is no Pressure Applied to the FSR, its Resistance will be greater than 1MΩ, with the Total Pressure applied to the Resistance it will be 2.5kΩ Two Pins extend from the Bottom of the Sensor, making it friendly to the Breadboard. are simple to set up and great for detecting pressure.