Designed to mount a pannier bag that attaches to a 10mm rod to a wall or slat wall.  Specifically, it was designed to mount the Ortlieb Sport-Roller Classic (https://www.ortlieb.com/en_us/sport-roller-classic+F6310).  To mount this to a slat wall, print this mount: https://www.prusaprinters.org/prints/77915-slat-wall-1u-plate-a