deck prisms
They are deck prisms. Devices to scatter light below deck. I have a pair which were factory standard on my O'day 28. Two of them in the v-berth. However mine are simple lexan plates which are flat to the deck and recessed inside the v-berth. The ones on the web site link are a new shape on an old idea. Keep in mind that they stick down and intrude into the salon area and could be head knockers if your boat is under 6 1/2 feet of standing head room below.They look pretty and the light is very nice without heating the area they serve.Mike