This article explains where to find the DevViewer tool, which helps you find hardware device ID's for device blocking in Symantec Endpoint Protection (SEP).
DevViewer shows the windows hardware devices tree. It allows you to easily find and copy the GUID or Device ID for a device, to use in an Device Blocking policy in the Symantec Endpoint Protection Manager (SEPM) console. The tool can be used with Symantec Endpoint Protection 12.1 and 11.0.
Depending on the version you use, DevViewer appears on CD2 under Tools\NoSupport\DevViewer, or on the installation disk Part 2 Tools under DevViewer.