A handy person from charlotte, nc says:
January 18, 2016
Jeld Win casement window bubble seal. Looks like it might match up to 58-183, but bubble looks a little small in comparison. Looking for a suggestion. Thank you, Tate
Dave from SWISCO responded:
January 20, 2016
Our 58-055 is a hollow bubble that may work as a substitute. It seems to have same off set leg like the one you show in your pictures. I can't quite make out your size, though, so look it over and see what you think.