Filtering on the Tech Overview, makes it easy for you to get an overview of a specifc part of your course. Maybe you want a map of your irrigation system, all eletronics or only the trees - you can do this with Filters.
You can filter on Element Name (e.g. Sprinkler, Tree or Cable) and the Name and Description you have given the elements.
If you want to show all elements related to irrigation, you can comma-separate your search and add e.g. "sprinkler, water box, hydrant" to the Element Name filter to get all elements of those specfic types.
If you have added the make and model to your elements in the name or description fields, you can add that to the filter to make it more effective. Adding e.g. "Toro" to the Name filter combined with the filter above, gives you only parts of the irrigation system manufactured by Toro.