Black PVC 2 inch x 2 inch slip union by Aqua Ultraviolet.
Winterizing your Aqua Ultraviolet units - 4:27 minutes (provided by Aqua Ultraviolet)
This video shows 2 methods of winterizing your Aqua Ultraviolet Classic UV unit. The first method will require 2 of these unions. The second method uses the Winterizing Cap
Manufacturer's Part #A40116