A magnet bar pair with keepers is a scientific instrument used to study magnetism. It consists of two cylindrical bar magnets and two metal keepers. The bar magnets are made of a ferromagnetic material and are magnetized along their length. The metal keepers are used to maintain the magnetic field of the magnets. When not in use, the keepers are placed over the ends of the magnets to prevent them from losing their magnetic properties. The magnet bar pair with keepers is commonly used in physics classrooms and laboratories to demonstrate magnetic fields and magnetic induction.