"Newly Updated (10/1/25) An Underquilt protector is a secondary layer of lightweight fabric that hangs below the underquilt and/or hammock bottom. Wind, if not blocked can rob your underquilt of heat and temp rating, so it’s important to block it in cooler conditions especially. The Underquilt protector does just that and it also allows for the use of a smaller tarp than would otherwise be needed. It also can be used as extra storage space under the hammock, and has a zipper which allows you to zip your whole kit up together, without having to take your setup apart. The UQP-10 fits the Original Blackbird and Traveler models, the UQP-11 fits the Blackbird XLC, Eldorado, and Traveler XL models.
 
Please note: The updated Underquilt Protector design is not compatible with Gen2 XLC or Eldorado Winter Topcovers."
 
The above wording is straight from Brandon, and his team at Warbonnet Outdoors.