Device targeting allows you to target your ads to people based on the device they're using.
Setting device targeting
You can set targeted bid adjustments for tablets, mobile phones, and desktop computers. By clicking "Devices" in the page menu, you can set your ads to target specific devices:
Computers: These are desktop or laptop devices with screens larger than 7" in diagonal.
Mobile: These are hand-held devices that include a phone.
Tablet: Tablets are mobile devices that don't necessarily include a phone.
TV screens: These are devices that stream TV content such as smart TVs, gaming consoles, and connected devices like Chromecast. This targeting option is only available for Display and Video campaigns.
Advanced options are available for Display and Video campaigns that allow you to target specific device types, operating systems, device models, and ad inventory (spaces where publishers allow ads to run), as well as carriers and wireless networks. Targeting specific devices narrows your reach to those devices. Some advanced mobile and tablet targeting options aren't available for other campaign types.
For example, you're selling accessories for mobile phones and you want to show your ads to people who own Mobile Device X. With device model targeting, you can create a message in your ad that's a lot more focused: "Customized Cases for Mobile Device X".