Diametrically magnetized magnets are magnetized across their diameters, so that the north pole is on one curved side and the south pole is on the opposite curved side.
These magnets provide the key to rotational movement, they can be used on the end of a shaft to provide drive or you could produce a magnetic rack and pinion system by using one of these working with a line of north and south alternating pole magnets.
The F679 (20mm (0.79") diameter x 20mm (0.79") thick) diametrically magnetized magnets are the strongest in this range and will engage each other from a distance of 100mm (3.94"). If you fix two of these magnets onto non-magnetic shafts and turn one of them, the other one will turn in synchronisation simply by the magnetic coupling that exists between them.