With this old version, the screw is affixed from the top. Feet sold separately.
If your lower base plate is not affixed with a screw you may have the older rubber version that slips over the outside of the main lower base. These are not interchangeable, and you would need to purchase the newer base cover as well as the entire newer lower base.
WARNING: This product can expose you to chemicals including lead, which are known to the State of California to cause cancer, birth defects, or other reproductive harm. For more information, go to www.p65warnings.ca.gov.