The pull force of a magnet is the force required to remove a magnet from a surface in three scnearios: when sandwiched between two peices of mild steel, when attached to a single piece of mild steel, and when attached to another identical magnet. One can expect a pull force similar to those quoted only in ideal conditions. Corroded steel, or steel of a different composition will change the pull force. The distance between the magnet and the surface it is attracted to will also affect the pull strength, as well as the direction in which the force is applied, relative to its axis of magnetization.