This example shows how to mask the Gain block and promote only the Gain parameter to the mask, while hiding the other options and adding custom parameters.
Right-click a Gain block in your model and select Mask > Create Mask.
The Mask Editor appears.
Select the Parameters & Dialog pane.
Click the Promote button. .
The Promoted parameter selector dialog box opens.
Select the Gain parameter in the Promotable parameters table and click the right-arrow button to add to the Promoted parameters list.
Click OK to return to the Mask Editor.
Double-click the Gain block. The new mask opens, showing only the promoted Gain parameter and custom parameter.
Look under the mask to see the underlying Gain block dialog box. You can see that the Gain parameter is now disabled because you have promoted it to the mask.