Airstream does use a coupler that has a rolled lip around the front edge and
the only place I could find a coupler lock to fit was at the local AS
dealer. Its model G-37 made by Guardian Industries in Tulsa OK and it fits
over the lip and covers the bottom of the coupler. I think I paid around
$45 for in last July. Guardians web site is at
http://www.guardianhitch.com/
Don (MI)