The drain screen was part of the original shower floor. It broke out over time (plastic). I got a new brass one 3 1/2 inches -- but am not sure about filing the old hole a bit bigger to make the new drain work.....
Is this shower floor tiled, fiberglass, something else? Need to know that to try to help.
Important note - I'm not a pro
Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013