DV360 Creative Specs - Native Display and Native Video

Native Display ad creative specs:

Brand logo: 1:1 ratio
Image: Use rectangular image here, 1200×627 pixels 
Square Image: Though it says optional, DO NOT PUT AN IMAGE HERE
Long headline: 50 character max
Short headline: 25 character max (Must enter either a long or a short headline)
Long body text: 140 character description (Use long body text) 
Short body text: 90 character description - Required field, though it will not render on Sharethrough inventory

Native Video ad creative specs:

Brand logo: 1:1 ratio
Video source file: mp4 file 
Cover Image: Use rectangular image here, 1200×627 pixels 
Long headline: 50 character max 
Short headline: 25 character max (Must enter either a long or short headline)
Long body text: 140 character description (Use long body text) 
Short body text: 90 character description - Required field, though it will not render on Sharethrough inventory

Here is a tool to help you resize your images to the DV360 specs:

http://generator.sharethrough.com/thumbnails/new