Individual hairs tricolored: dark gray at the base, buffy (yellowish brown) in the middle, and brown or reddish brown at the tip.[1] It is the smallest bat species found in the eastern and midwestern US.[11] Individuals have a forearm length of 31.4–34.1 mm (1.24–1.34 in) and weigh 4.6–7.9 g (0.16–0.28 oz).[12] Its forearms are reddish, contrasting sharply with the black membranes of its wings.[13] Its wingspan is 21–26 cm (8.3–10.2 in).[14] It has a dental formula of 2.1.2.33.1.2.3 for a total of 34 teeth.[12]