and displays good low temperature operability in the preferred embodiment of the connector spacer the clip is formed to include a pair of channels 20 22 which are receptive to adjacent frame members 12 of adjacent panels as indicated in fig5 each of the channels includes an inner wall 24 having upper and lower ends the upper ends are connected by an integral web 26 the lower ends of the inner walls 24 merge into outwardly extending bottom walls 28 which in turn merge into upwardly extending outer walls 30 a stiffener and spacer 32 is secured as by a suitable adhesive to the inwardly facing surfaces of the inner walls 24 the stiffening spacer 32 may be t shaped in cross section as shown in fig4 the channels 20 22 are dimensioned so that their width along the bottom wall 28 corresponds to the width of the frame members 12 the upper ends of the outer walls 30 however are inclined inwardly at a slight angle a of the order of a few degrees thus the spacing between the inner and outer walls 24 30 is somewhat restricted at the upper entry end the outer walls 30 and bottom walls 28 are sufficiently flexible so that the walls 30 can flex to expand the width at the upper end of the channel thereby to.