I don't know of a built in way to filter them.  Maybe someone else can chime in.

You can write a script to copy the hanger rod size to a field you can filter like Pallet or item number.

The below script copies the rod diameter to both item number and Pallet.

select item.Cid
case 838
dim rod=item.option["Drop Rod Diameter"].value
item.pallet=rod
item.number=rod
end select