Mfg's page: https://8020.net/
Note that there are several inch and metric pattern sizes available. jakemartin used 1/2 height Series 10 (1 inch), p/n 1050: https://8020.net/shop/1050.html The std thread size for Series 10 is 1/4-20, but smaller sizes are available. Note that you can order the extrusion cut to the exact length desired, and the cuts are both square and completely burr-free. They can also do other custom stuff limited only by your imagination and wallet.
We use this stuff at work and I can not say enough good about it. I frame whole production machines with it.