Hey Dave, how you doing? I think you may be looking for a SP-1026 Safety Grate Insert. (They have 1.5" MPT, have a bowed out separators, the diameter vertically and then 3 more horizontally)

If you need one, just let me know, I'll pop one in the mail for you (for some strange reason, I have a bunch of small pool parts floating around the house - most are on the shelf down by the washer/ dryer - - at least they're clean )