Tandem creatives, also known as roadblocks or site takeovers, are multiple In-page, Floating, or Expanding units that are linked together to serve on the same page at the same time.
Basically, a Tandem creative is created by trafficking two different-sized In-Page units together in DFA or DFP. There are additional features that you can include when building a Tandem creative, such as synchronizing animation of the two units.
This build guide walks you through the process of using the Local Connect component 
to synchronize the animation of two In-page units and setting up roadblocks in the DoubleClick Studio Web UI Preview.
This guide assumes you understand how to build a DoubleClick Studio In-page creative. If you don't, see the In-page build guide.
Traffickers, learn more about unique Tandem trafficking information in DFA or DFP.
To start building a Tandem creative, see Step 1: Set up your files and follow the workflow in the side panel.
Watch a video about Tandem creatives (15:28)