Patent ID: 8760857

Claim:
A universal serial bus (USB) device, comprising: a base comprising a body, a pair of arms extending from one end of the body and parallel to each other, and a pair of stopper portions extending from inner sides of the pair of arms, the body and the pair of arms collectively defining a receiving groove; a head rotatably connected between the pair of arms; and a pair of wheels, respectively fixed to two sides of the head and located between the head and the pair of arms, each of the pair of wheels comprising a friction wheel and a stopper wheel extending coaxially from the friction wheel, each of the stopper wheels comprising a plurality of projections located on a circumferential periphery thereof and spaced from each other; wherein when the wheels are rotated in a same direction and then the rotation is stopped, at least one of the projections of each of the stopper wheels engages with a corresponding one of the stopper portions of the base to position the head relative to the base.