In the OpenShift Web Console, go to "Observe" > "Alerting". Switch to the "Silences" tab and click on the "Create silence" button. In this dialog, click on the "For..." dropdown menu. The first item "-" stands for the custom expiration period, however, this is not immediately apparent. See also the attached screenshot.

Can the "-" be changed to something like "Custom" to make it very clear that the user can select this item to define a custom expiration period?

Alternatively, it could be easier for the user if the custom expiration period could be directly entered in the dropdown menu widget.