We have that and it is a plug for bunk bed lights. The lights come with a coiled wire that plugs into that outlet. The lights also come witha hook to put on the roof support poles over the bed.
My questions are:
1. Can we still buy those outlets or do we have to upgrade to the newer style which is like a headphone jack?
2. Where can we buy another one of the portable bunk lights? The trailer only came with one from the previous owner. It would be nice to have 2. But all we can find are the ones with the headphone like jack.