> For the complete documentation index, see [llms.txt](https://developer.harness.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.harness.io/feature-management-experimentation/use-fme/experimentation/setup/metric-selection/guardrail-metrics.md).

# Selecting guardrail metrics

### Overview <a href="#overview" id="overview"></a>

Once you've [created an experiment](/feature-management-experimentation/use-fme/experimentation/setup/index.md), you can assign guardrail metrics to your experiment.

### Assign guardrail metrics <a href="#assign-guardrail-metrics" id="assign-guardrail-metrics"></a>

1. Navigate to **Harness FME** > **Metrics** and click on a metric.
2. Click the Edit icon next to the **Metric category** section.
3. Select `Guardrail metrics` from the dropdown menu.
4. Click **Apply**.

{% hint style="info" %}
If you add a guardrail metric as a key metric to an experiment, it will be assigned as a key metric for that experiment only.
{% endhint %}