--- /dev/null
+.. _max_element_length_3d_page:
+
+*******************
+Element Diameter 3D
+*******************
+
+This quality control criterion consists in calculation of the maximal length of edges and diagonals of 3D mesh elements (tetrahedrons, pyramids, etc). For polyhedra the value is always zero.
+
+**To apply the Element Diameter 3D quality criterion to your mesh:**
+
+#. Display your mesh in the viewer.
+#. Choose **Controls > Volume Controls > Element Diameter 3D** or click **"Element Diameter 3D"** button in the toolbar.
+
+ .. image:: ../images/image43.png
+ :align: center
+
+ .. centered::
+ **"Element Diameter 3D" button**
+
+ Your mesh will be displayed in the viewer with its elements colored according to the applied mesh quality control criterion:
+
+ .. image:: ../images/max_element_length_3d.png
+ :align: center
+
+
+**See Also** a sample TUI Script of a :ref:`tui_max_element_length_3d` operation.
+
+