diff --git a/cura/Machines/MaterialManager.py b/cura/Machines/MaterialManager.py
index 5b07811d34..5e674965b3 100644
--- a/cura/Machines/MaterialManager.py
+++ b/cura/Machines/MaterialManager.py
@@ -13,6 +13,11 @@ from .MaterialNode import MaterialNode
 from .MaterialGroup import MaterialGroup
 
 
+#
+# MaterialManager maintains a number of maps and trees for material lookup.
+# The models GUI and QML use are now only dependent on the MaterialManager. That means as long as the data in
+# MaterialManager gets updated correctly, the GUI models should be updated correctly too, and the same goes for GUI.
+#
 class MaterialManager(QObject):
 
     materialsUpdated = pyqtSignal()  # Emitted whenever the material lookup tables are updated.
diff --git a/cura/Machines/QualityManager.py b/cura/Machines/QualityManager.py
index 5783f54064..4115b710e0 100644
--- a/cura/Machines/QualityManager.py
+++ b/cura/Machines/QualityManager.py
@@ -147,6 +147,11 @@ class QualityNode(ContainerNode):
         quality_changes_group.addNode(QualityNode(metadata))
 
 
+#
+# Similar to MaterialManager, QualityManager maintains a number of maps and trees for material lookup.
+# The models GUI and QML use are now only dependent on the QualityManager. That means as long as the data in
+# QualityManager gets updated correctly, the GUI models should be updated correctly too, and the same goes for GUI.
+#
 class QualityManager(QObject):
 
     qualitiesUpdated = pyqtSignal()