IPS has a bathroom, kitchen & dryer exhaust vent cap (SnapCap) that is easy to install, and adapts easily to a 3″, 4″ and 6″ connection.  SnapCap is constructed of heavy gauge aluminum or steel; has a counterbalanced damper (flap) and works with any CFM fan.
For more information, watch the Snap Cap video or check out the Snap Cap brochure.
If you have any questions, please don’t hesitate to reach out.