To lock the parts in place the lower tongues are each formed with a downwardly extending hook projection which is in interfering engagement with the lower edge, or ledge, of the window, making the cross beams captive against {HEAD ~ longitudinal withdrawal} from {TAIL ~ their seated positions} 
To lock the parts in place the lower tongues are each formed with a downwardly extending hook projection which is in interfering engagement with the lower edge , or ledge , of the window , making the cross beams captive against { HEAD ~ longitudinal withdrawal } from { TAIL ~ their seated positions }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL