Vision Furthering Devices (or Sunoculars as Esmé Squalor called them) is an eye-wear gadget that first appears in The Penultimate Peril. It is a combination of sunglasses and binoculars, and of which functions for that purpose. They were apparently inventions of V.F.D.. They were first seen by Esmé Squalor, who used them in order to look for the VFD crows that would carry the sugar bowl. Later on, Justice Strauss and Jerome Squalor (now volunteers) were seen wearing them for the same purpose.
According to the book, the sunoculars look like sunglasses, but as Lemony Snicket says:
"Instead of lenses, there were two large cones sticking out from the eyes, getting wider and wider until they stop, as wide as dinner plates, several feet in front of the person's face."