The one in front is a home-made tube trap with an absorptive side and dispersive/ reflective side sitting on its custom stand. When used alone they each help lock in central images and when used together at varying distances they can also maneuver the apparent image distance from the listener and front wall. 

When I discovered how well the ASC worked alone I built a pair of the black one you see.. the other isn’t in the room at the moment but can sometimes be placed at some point behind the listener’s head at varying distances from the rear wall...especially effective when used with a low-back listening chair. Anything that can improve the lissn’ing experience...!