A griper device mountable on a robot arm of a milking robot provided for automatically attach teat cups to the teats of a milking animal, the gripper device comprises an electromagnet from gripping teat cups made of a magnetic material, the electromagnet including a coil feedable with a current a core of a magnetic material arranged at least partly within the coil; and a support structure for holding the electromagnet. The core comprises two end and portions in a single face of the electromagnet wherein the two end portions constitute different poles of the electromagnet and are shaped to be engagable with each of the teat cups in a close fit.