Hey John, (Miles is working)
Thank you very much for your question. The screw that mounts the panel to the t-base is a 2.5" metal stem with a 5/16 - 18 thread screw. The length or span of the t-base on the floor is 18 3/4" long. Also here is a link to all the hardware that we offer for office panels systems hardware.
Please remember that On Time Supplies offers over 40,000 products for next day delivery, we also ship directly from over 350 manufacturers for huge savings and we offer the best customer service in the world.
We appreciate your question about the details of the Hon T-base stabilizing foot.