that is slightly less than the diameter of the end holes 35 and top openings 41 and 41 u2032 in the connectors 9 in the middle leg 47 of each tie 11 are a number of seats 51 the middle leg may be bent as shown to produce the seats 51 there are preferably a center seat 51 a and two side seats 51 b although that particular arrangement is not critical for the operation of the present invention a satisfactory diameter for the tie material is a circular rod of 0 19 inches diameter the end legs 49 may be approximately 1 50 inches long the length of the middle leg is variable as will be explained in detail presently with particular attention to fig5 the inserts 7 are embedded in the panel 5 at the factory for that purpose the connectors 9 an insert are retained in an aluminum mold represented by phantom lines 53 the connector tabs 27 and 28 cooperate with slots in the mold 53 to keep the inserts in place the presence of the two connectors 9 and 9 u2032 plus the fact that the connectors are double ended renders the inserts invertible in the mold consequently orientation mistakes when loading the inserts into the mold are eliminated it is preferred that the inserts be centered between the panel top and bottom surfaces 14 and 16 respectively for a panel that is 16 inches high and an insert with a 15 inch base 15 the longitudinal axes 43 of the connectors are then four inches from the top and bottom surfaces the inserts are further located so as to be centered on the grooves 36 a and 36 b accordingly six inserts are used for a 48 inch long.