 Sanborn's species is one of the smaller bonneted bats, measuring around in total length, including the tail, and weighing .They have rich blackish-brown fur, which is paler on the belly, and which allows it to be distinguished from the similarly sized, but more lightly coloured, dwarf bonneted bats that live in the same general area.Other distinctive features of the species include narrow wing tips, relatively well-developed teeth at the back of the jaw, and a higher jaw joint than in its close relatives.