Does exactly what it’s supposed to, are easy to fold into position along the inherent creases, and at a reasonable price. Raised and/or glossy elements are also still distinguishable through it. I'll likely be ordering at least a few more in the future.
One thing I don’t see mentioned in the product description is that, at least with the ones I was sent, there’s some sort of screen or wrap applied to the outer sides of the protector, which you might notice start to peel a bit when pushing the flaps into place (or at least, that’s how I noticed it). I’d wager it’s to add some scratch resistance to them, be it just for shipping or shelf-ware as well, but it does add something of a “cloudiness” to the look of whatever is inside. Whether that bothers you or not is really up to you, and admittedly I’m not personally certain they were intended to be removed, but they do peel off pretty easily, leaving a properly clear sleeve for your slipcovers.
This particular item fits slipcovers sized for standard VS-style Blu-ray cases as can be found on the replacement case page, including the 2 and 3 disc cases (the clear ones anyway; I don't have a 4KUHD to try these with at the moment). Note that they will likely not fit slipcovers from other, non-Vinegar Syndrome or non-partner labels which may be sized for deeper cases. I can confirm they do not work for Arrow or Grindhouse Releasing.