Laser Dinghy Lighting board
This s a bog standard lighting board, but fitted with a set of pintles to drop it straight onto the back of a Laser dinghy.
The board is held down by the bit of elastic, and the number plate slides in & out under the two bungee loops so can be easily moved from trailer to trailer, although there is nothing to stop you screwing one on full time.
One reflector is cracked, and TBH it's not seen the back of a Laser in the best part of 10 years, so I can't guarantee it's working, although it has lived in the garage all that time and lit up fine on it's last journey, so I'm reasonably confident it works! TBH if you look on it as a Laser transom adapter with free lighting board is probably the best option to avoid disappointment.
Cable to get the length of a Laser & a drawbar (~5m)!, 7 pin plug