SU5875 functioned as the western boundary for cut 5891, in which a cappuccina drain was constructed draining to the east. At its upper extent the function of 5875 remains unknown, perhaps functioning as a buttress for wall 5789 at its western extent where 5789 abut ashlar wall 5798. Alternately the upper surface may have functioned as a counter or horizontal platform of unknown function. The main purpose clearly related to the water features along the south side of Room 20, however.