- [JSON representation](https://developers.google.com/ad-manager/api/beta/reference/rest/v1/AdUnitSize#SCHEMA_REPRESENTATION)

Represents the size, environment, and companions of an ad in an ad unit.

| JSON representation |
|---|
| ``` { "companions": [ { object (`https://developers.google.com/ad-manager/api/beta/reference/rest/v1/Size`) } ], "size": { object (`https://developers.google.com/ad-manager/api/beta/reference/rest/v1/Size`) }, "environmentType": enum (`https://developers.google.com/ad-manager/api/beta/reference/rest/v1/EnvironmentType`) } ``` |

| Fields ||
|---|---|
| `companions[]` | ``object (`https://developers.google.com/ad-manager/api/beta/reference/rest/v1/Size`)`` The companions for this ad unit size. Companions are only valid if the environment is `https://developers.google.com/ad-manager/api/beta/reference/rest/v1/EnvironmentType#ENUM_VALUES.VIDEO_PLAYER`. |
| `size` | ``object (`https://developers.google.com/ad-manager/api/beta/reference/rest/v1/Size`)`` Required. The Size of the AdUnit. |
| `environmentType` | ``enum (`https://developers.google.com/ad-manager/api/beta/reference/rest/v1/EnvironmentType`)`` Required. The EnvironmentType of the AdUnit |