Abstract: The separation device of the invention is directed to a container having an interior surface defining a channel. The container further has an inlet and an outlet. On the interior surface of the channel are pole tips which may be in a sawtooth configuration having sharp angles facing the interior of the channel that generate a high gradient magnetic field in the channel. Within the channel may be incorporated separating material. The separating material eliminates the direct contact of cells with the magnetic pole material. The separating material, as well as the sawtooth pole tips also serves the purpose of creating a field gradient across the entire container to avoid the problem of zero field gradient in the center of the container where the velocity is greatest, and where more cells flow. The separating material is designed to cause a substantially unobstructed flow of medium through the channel so that unlabeled substances are not trapped in the separating material.