For coastal navigation, a life ring with a floating automatic light and 15 meter line is required.
Since I am doing mostly solo navigation, it is utterly useless for me, but I still have to comply with the regulations, so I purchased the cheapest plastic life ring (30 USD). In the hindsight that was a big mistake, because it was big and occupied a lot of space, and I should have purchased the more expensive, but compact horse shoe.
However, I have found a good place for it over the starboard lazarette hatch and it even looks cool.
The release "mechanism" consists of stainless steel peg around which the line from the life ring is wrapped.
The automatic light operates by gravity. At first I did not understand how it operated. There is a weighted lead piece inside which slides over and presses the battery contacts when the light is turned upside down.