These cowl vents are made of flexible PVC (polyvinylchloride) which has very good UV resistance. The cowls revolve and are removable.
The cowl is secured by a knurled ring nut (collar). No tools are required as the ring nut can be loosened easily by hand.
The included ring nut (collar) and mating deck flange (attaches to dorade box) are made of a hard plastic.
An insect screen and solid stainless steel cover plate to close off the cowl vent can be purchased separately. See Accessory Products, below.
The accessory Dorade Box (sold separately) mates with the cowl vent ring nut and catches and drains water that enters the cowl.