Hi Elaine, I am trying to control the opacity/transparency of maps..however it seems to me that these two different concepts within the framework although they are used to achieve the same effect... My understanding is that transparency controls the surface being displayed whereas opacity controls the opacity of the color assigned to the surface. Is there room to unify these two concepts in ChimeraX? On an operational level, how do I control the opacity of a color in chimeraX commandline? Currently I am assigning colors based on hexcodes for specific shades... but there isnt a way to take into account the opacity of that shade with hexcodes only... Best, Pranav -- Pranav Shah Postdoctoral Research Fellow. Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK