This latch was used on many windows and doors in the 1950s and 1960s...even as late as the early 1970s (for example 1971 Silver Streak trailers). It was used on Hehr Standard windows, Hehr Hall-Mark 12 windows and several others. Not used after 1965 on Airstreams.
It was mounted on the inside of the trailer to securely latch doors and windows closed. Mounting holes are approximately 2-3/8" on center, but are elongated to fit a range of mounting hole spacings. Comes with a catch, but the catch may be different than the one used on your trailer.
Zinc plated. Paint it to match the interior of your trailer or leave it as bare metal.