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