To find entities that are near the selected entities, within a specified distance, you can use the Nearby Function.

The following example shows how to find elements nearby a system, within a distance of R = 20 mm.

In the Options menu you can choose between show and isolate.
Sphere and Box are available as search methods.

 

Click Entities to display and select from the entities list.

 

Click Components and choose Systems from the list and select the desired System.

Enter 20 in the Radius input field.

In order to isolate the found elements, as in the following image.