Each device that a user owns has a unique identification code that can be targeted. A desktop computer, laptop, and phone belonging to the same user will each have a unique Device ID. You can load these ID numbers into Pontiac to deliver campaigns directly to a user’s specific device. This Audience has a limit of 100,000 Device IDs per list. 
In the ‘Custom Audience’ section, enter each Device ID on an individual line, including the corresponding device type prefix, in the following format:
Line format: [Device ID]
Example: 0-123e4567-e89b-12d3-a456-426655440000
Device Type Prefixes:
0 –  IDFA (Apple ID for Advertising)
1 – SHA
2 – MD5
4 – OPENUDID
5 – AAID (Android Advertising ID)
6 – WINDOWSADID (Microsoft Advertising ID)
Once saved, this audience can be associated to any Line Item in the seat. Custom audiences are associated to the campaign in the ‘Audiences’ section of the Line Item creation screen. Select ‘Associate Segments’ and choose the audience from the ‘Custom Audiences’ dropdown.