This is colum sold by Home Depot with their pergola kits.
Left from the job.
The white is the item actually for sale and the ivory shows installed one as a sample.
Made with some composite that has some load capacity, but for structural strength you can put 4x4 or rounded 6" lumber inside. Don't email me unless you are ready to come to see it and send me your phone number. I work at home and can be available.