ITEM NAME:New HC-SR501 Infrared PIR Motion Sensor Module for Arduino Raspberry pi B AuF Gw.It has a high value of 3.3 volts and a low of 0 (it is either on or off). The entire sensor with the board is 32mm by 24mm (standard pir motion sensor). Either one will work. 1pc New HC-SR501 Infrared PIR Motion Sensor Module.