# MediaTailor bumper ad insertion
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Bumpers are short, non-skippable video or audio clips that play at the start or before the end of an ad break with AWS Elemental MediaTailor.

 The following conditions apply to bumpers: 
+ Bumpers must be 10 seconds or less.
+ Bumpers can be inserted at the start of an ad break, directly before the end of an ad break, or both.
+ Bumpers play during every ad break in a playback session unless pre-roll is configured. If pre-roll is configured, bumpers won't play during the pre-roll break. Instead, they will play in every subsequent break after the pre-roll.
+ For HLS, you must include the `duration` attribute with each SCTE-35 `EXT-X-CUE-OUT` tag.
+ Bumpers are transcoded to match source content.
+ You are not charged for bumpers.

## Configuring bumpers
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To use bumpers, configure the bumper URLs with the MediaTailor console, MediaTailor API, or the AWS Command Line Interface (AWS CLI). You can configure a start bumper, an end bumper, or both. Bumpers are stored on a server, such as Amazon Simple Storage Service (Amazon S3). The bumper URLs indicate the location of the stored bumper asset(s).

Example start and end bumper URLs:

Start bumper URL: `https://s3.amazonaws.com/startbumperad`

End bumper URL: `https://s3.amazonaws.com/endbumperad`

### Example
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The following is an example of bumper ad behavior.

**Example 1: Start and end bumpers**  
In this example, start and end bumpers are enabled. The ad decision server has 50 seconds of personalized ads to fill a 70-second ad break. The 10-second start bumper plays at the start of the ad break, 50 seconds of ads plays, then the 10-second end bumper.

![\[This illustration shows an ad break filled with a start and end bumper and ads.\]](http://docs.aws.amazon.com/mediatailor/latest/ug/images/bumpers.png)