An adult sugar glider is approximately 11 inches long from his nose to the tip of his tail, but most of that (6 or 7 inches) is tail. In shape and size they are very similar to our American flying squirrel.
The fur is very soft, and gray in color, with a white belly and a black stripe from the nose over the head and down the back. The last two inches or so of the tail is also black. The gray of the body meets the white of the belly right at the edge of the webbing between front and back legs, which creates a striking ripple effect at their sides when the webbing is not stretched taut. They also have smaller black stripes that run down each leg.
Colors in the wild can vary, with the white areas ranging from white to cream to yellow, the grey areas from grey to brownish grey or tan, and the stripes from black to chocolate brown. Some have white-tipped tails. New colors are emerging in captivity, including albinos, black-eyed whites, blonde and platinum, and various mottled color combinations. There are photographs of some of the color variations on Sandman's website.
The ears are hairless and on the largish side, and turn toward sounds like a cat's ears. Their eyes are very large, as you would expect in a nocturnal animal, and black.
Their face is much pointier than that of a flying squirrel. The pointy face, combined with the ears and the big eyes, gives them a look that is somewhat reminiscent of a bat. (A very cute bat.)
The glider's tail is weakly prehensile and is sometimes used for carrying twigs or leaves to their nests. Babies also wrap their tails tightly around their mother's tail or leg to help help them hang on while Mom leaps around.
The tail is very long, so it can be used as a rudder and for balance as they glide from tree to tree. Their hands and feet are very deft and capable and they use them as well as any monkey. Their hands are shaped much like our own, with four fingers and an opposing thumb. The feet have four toes and a nailless "thumb". The first two toes almost look like one toe split down the middle, and all the fingers and toes have little pads on their undersides.
The female's pouch opening is a vertical slit, about a half inch long, in the lower middle of her abdomen -- about where you would expect to see a belly button. The male's testicles are located in a furry little lump at that same spot on his belly, and the genitalia (two of them, actually) is farther back, at the base of the tail. Baby sugar gliders are easy to sex before their fur grows in, by the presence of either the pouch opening in females, or the testicles in males.
An anatomical odditiy they share with opossums is the bifurcated genitalia -- there are actually two shafts. Normally they are retracted, but they often show when the male is afraid or excited. The female's anatomy is also similarly divided, and can support two simultaneous pregnancies, holding one in a sort of stasis while the other is developing.