The FAMCO Plastic Bath Fan / Kitchen Exhaust Roof Vent with Stem, also referred to as a BVDS Exhaust Vent, is made of High Density Polyethylene (HDP). HDP is one of the most versatile and widely used plastics available. Outdoor integrity is maintained in this, and all of our plastic products, by the addition of UV inhibitors, which protect the material from deteriorating in the sunlight. The stem on the BVDS can be removed for hard connect applications and the screen can be removed for use as a roof mounted dryer vent.