Polarized hull plating
Polarized hull plating was a defensive technology that preceded shields. In a battle situation, electromagnetic power could be applied to the hull materials, making them several orders of magnitude harder. This technology was used on starships of Star Fleet such as the NX Class in the 22nd century. Unlike shields, polarization cannot be amplified to reinforce a specific direction. The amount of polarization on the ventral sections of the ship is the equal on the dorsal.
Polarizing a hull on a 24th century starship can be used as a method of disrupting a tractor beam or masking a starship's approach.