The upper parts are yellowish gray, bright brown, chestnut, or black. The underparts are yellowish, buffy, brownish, or white. The tail is generally the color of the back. The tail is not flat like that of Glaucomys. The limbs are united by broad, fur-covered membranes that extend from the sides of the body to the toes.
Females have six mammae.
Giant flying squirrels inhabit forests in the hills and mountains. In central and eastern Taiwan they have been observed on the rocky cliffs of deep valleys. These squirrels are nocturnal and arboreal, usually being found at heights of 15-30 meters or above in the trees. They spend the daylight hours in hollow trees or branches and become active after dusk. They travel through the treetops in a squirrel-like manner, but when a branch or a tree is too distant to reach by an ordinary leap, they go to a high branch and leap toward the objective, extending the membrane as they spread the arms forward and out, and the legs backward and out.