between the pair of two glass panes the core spacer and the cord extend around a periphery and go around corners between the panes in an airtight manner to form an insulated assembly also the cord has a diameter no greater than about 10 of a width of the core spacer a method for manufacturing the insulated assembly is likewise disclosed application_number US 17316802 A description in fig1 a first embodiment of a rubber core spacer 10 noncircular in shape is shown with a top side 12 a bottom side 14 a short side 16 a long side 18 and two diagonally cut corners 20 and 22 a single nonheating nonstretchable centrally positioned fiberglass cord 24 is embedded in the rubber core spacer 10 when the latter is manufactured so that the core spacer 10 is not stretchable the preferred rubber formulation for the spacer 10 is an ethylene propylene diene monomer epdm polymer with fillers however other solid rubber materials may be suitable the height h varies according to the width selected for the spacer 10 thus the height h may range from as little as one quarter to three quarters of an inch or greater the cord 24 is cylindrical in shape and has a diameter of at least 0 01 inch which is sufficient for the cord 24 to be effective inside the spacer 10 however the preferred diameter is 0 02 inch in fig1 it can be seen that the cord 24 has its diameter no greater than about 10 of the width of the spacer 10 in fig2 a first hot.