Abstract: A corner key device is shown for use in a glass thermal pane structure assembly, the key device is used with longitudinally extending spacer means that may be formed into a rectangular spacing frame to hold the several sheets of glass forming the pane separated. The corner key means is made in the shape of a straight channel adapted to be telescopically interfitted with the spacer means and this straight lineup of channel shaped corner and spacer elements may then be coated on the outside of their walls with a layer of a hot melt sealant. Then the corner key devices are then bent at right angles to produce the rectangular frame adapted to engage the glass sheets around their perimeter to produce a seal between the glass sheets and spacer means and bind them together to form the finished thermal pane.