This unit mounts on a 1" outer diameter pole easily and is held in place by its included Complete Clamp. It handily catches seed spilled from above and is a great favorite of cardinals and other ground feeders. The broadly curved edge prevents squirrels from getting to your feeders when placed below them and 4' or higher on the pole. This unit can also be filled with sunflower seed or cracked corn and used as an additional feeder.