They are for the power feed stops, there is a tee nut on the opposite end of the small thread with nut that you can see on the two stop blocks but you could also make manual stops and an a block for them to touch using the two tapped holes on the front.

You can see them fitted to this SX3.5DZP

Edited By JasonB on 08/01/2020 19:54:44
Edited By JasonB on 08/01/2020 19:56:09