ZITRADES HC-SR501 Human Sensor Module Pyroelectric Infrared Sensor for Microcontrollers and other Electronic Projects BY ZITRADES Working Voltage : 5V(DC) Startup Time: 2 Seconds to get a measure on room volume Left Knob: Controls output latch delay (Between left-most 2 and right-most 300 seconds) Right Knob: Controls center of best detection (Between left-most 3M and right-most 7M) Dimension: 3.2cm x 2.4cm x 1.8cm (approx)