Sig Pro slides, at least those manufactured in the US, have no markings whatsoever on the right side, but have "SIG SP 2340" or "SIG SP 2009" roll-stamped on the upper-front flat, and the following two lines of text roll-stamped on the lower flat:
SiGARMS INC.
Interestingly, some Sig Pros have the above two lines of text roll-stamped behind the disassembly notch (like the photo below), and some instead have the same text roll-stamped in front of the disassembly notch.
Here is a photo taken from the left side of a Sig Pro SP 2340 slide showing the text that is roll-stamped:
Note that the SP 2022 is a Sig-Sauer pistol, as stamped on its slide:
