How to Find My Desire Fixture's Serial Number

D40 and D60 fixtures, including XT and XTI versions, have their S/N labels located behind the glass in front of the emitters, on the rim of the fixture opposite the gel clip, as shown below.

While the serial number label will in most cases be the quickest way to find the serial number, it may be difficult to access or read in field conditions. In this case, on fixtures which have a user interface, you can find the serial number in the Advanced Settings -> Diagnostics -> About Fixture menu, as shown below: