This is a force sensing resistor with a round, 1.27cm diameter, sensing area.
This FSR will vary its resistance depending on how much pressure is being applied to the sensing area. The harder the force, the lower the resistance.
This FSR can sense applied force on sensing area in the range of 0g-10kg.
Two pins extend from the bottom of the sensor to mount the FSR.
This sensor is simple to set up and great for sensing pressure, but you may not want to use it as a scale for it is not incredibly accurate.