The technology provides for an extension member configured to direct a magnetic field from a magnet to a Hall Effect sensor to facilitate detection of magnetic field. By varying the dimensions of the extension member, which may be any arbitrary shape, the relative positions of the magnet and the Hall Effect sensor may be less constrained by the reach of the magnetic field of the magnet, thereby allowing more design possibilities. The extension member may be used in a case, where the extension member may facilitate detection of whether the case is open or closed, the extension member may further provide magnetic attraction to keep the case closed.