Internal mesh dump pockets are large, open-top pockets inside your jacket with no zipper closure. They're designed for quick stashing of items you need to grab fast—like goggles when you head inside for lunch, gloves when you're warming up, or even climbing skins if you're touring in the backcountry.
These pockets are incredibly convenient because you can drop items in without fumbling with a zipper, and the mesh lets air circulate, which helps damp gear dry out a bit. They're especially handy for resort riders who frequently stash goggles or gloves between runs, and for backcountry skiers who need quick skin storage on transitions.
The main downside is that since there's no closure, anything inside can tumble out if you take your jacket off or lean the wrong way. If you tend to peel off layers at lunch or ride with your jacket unzipped, you'll want to be mindful of what you leave in there.