Filter System Types and elements Together

Hi,
I am fairly new to dynamo and feel like this is an easy fix but i have just hit a wall. I am trying to match elements of a system with a system type selection that is chosen from a drop-down box.
the lower portion of the code gets user input for mechanical system type insulation type and thickness. this is all good and i have managed to get this to work (select return air etc). the issue is applying the correct system type to the element selection (ducts, duct accessories etc) and filtering out those elements i don’t want (different system type).
can anyone help and point me in the right direction?
any help is appreciated.

Hello @stacey.hennigL6B3T and welcome here…could “indexof” or “list all indicies” help

The issue is that the == node will not compare elements. You can either use the system’s Element Id (which is comparable) or, as @sovitek said, you can use AllIndicesOf.