# Set Up Feature Flags | Sentry for PHP

## [Requirements](https://docs.sentry.io/platforms/php/feature-flags.md#requirements)

* [Sentry SDK](https://docs.sentry.io/platforms/php.md) version `4.18.1` or above.

## [Enable Evaluation Tracking](https://docs.sentry.io/platforms/php/feature-flags.md#enable-evaluation-tracking)

### [Generic API](https://docs.sentry.io/platforms/php/feature-flags.md#generic-api)

You can use the generic API to manually track feature flag evaluations. These evaluations are held in memory and are sent to Sentry on error and transaction events. **At the moment, we only support boolean flag evaluations.**

Each event can record up to 100 feature flag evaluations; if more are sent, only the most recent 100 are kept.

```php
\Sentry\addFeatureFlag('test-flag', false);

\Sentry\captureException(new \RuntimeException("Something went wrong!"));
```

Go to your Sentry project and confirm that your error event has recorded the feature flag "test-flag" and its value "false".