This Magnetic World building set has durable construction which means that it will stand up to the rigors of everyday play. The sticks in this set are made of a solid steel core and covered with plastic to make them not only strong, but it also allows more of the magnetic force to be utilized making them stronger. The steel balls included are not magnets, but will securely stick to the magnetic bars. The items included in this set are 40 steel balls, and 40 bars. The parts in this kit will fit perfectly with parts from other sets. This will allow you to build even larger items.