6" refers to the size of the hold footprint that this volume will accept.
The angle of the walls on the volume: 60 degrees
Measurements: 18" x 18" x 7-3/4" off the wall
Zinc Round Base T-nuts pre-installed: 4
Please do not drill spinner screw holes or any other holes into Polyurethane Volumes. You can weaken the structural integrity of the product. This practice also voids our warranty.