Samsung SyncMaster XL20 - Manual (Page 16)

LED indicators Turns on a red light when a product such as a scanner is being
used.
Illuminance sensor Measures the surrounding illuminance.
Sticky plates Helps to attach the calibrater firmly to your monitor.
Color sensor Adjusts the brightness of your monitor so that it matches the actual
color sense.
Scratch prevention
pad
Protects the monitor when attached to it.
2) Connecting the Calibrater
Connect the USB cable of the calibrater to the USB port on the right side of your monitor.
3) Using the Cradle