As a skylight specialist I recommend VELUX Skylights and VELUX Products!
This is an existing acrylic dome skylight that has been manufactured by another company. This unit was installed by roofers only 8 years ago. This unit is a self flashing skylight and is sealed to the roof with caulking. (Caulking deteriorates with time!) Always install VELUX Products and have them installed with a high grade ice and water membrane.
Once you do your research you will find that VELUX units are the best on the market.