I looked at it again. I would say the inner baffles are 1/16th inch. and the tops are 1/8th inch. They aren't very flexible and should withstand anything as the baffles in the sump that I got are not much thicker if not the exact same. Well at least the ones that I took out. I replaced the baffles in that one with some thicker plexiglass as I had an old plexi tank sitting around.