A contactor apparatus used in automatic testing of integrated circuits is provided. The invented apparatus, or assembly, enables the rapid automated test transition from testing a plurality of devices of a first body shape to a plurality of devices having a second body shape, where both types of devices have electrical contacts arranged within a device contact plane and according to a common grid pattern. The common grid pattern may be arranged along an X and an orthogonal Y axis, where contact points are spaced at identical intervals along each axis, e.g. a contact point at each 0.8 millimeter by 0.8 millimeter location, or where the contact points are spaced at differing intervals in each dimension, e.g. a plurality of contact points located at 0.8 millimeter lengths along the X axis and at 1.2 millimeter lengths along the Y axis. The contactor may have a plurality of apertures useful to simultaneously test a plurality of devices.