Polarized hull plating

Polarized hull plating was a defensive armored hull technology used on shuttles and starships. Before the development of deflector shielding, hull polarization was the primary defensive measure for starships against enemy weaponry.

Unlike with deflector shields, transporters could be used by a starship when it's hull plating was polarized.

History
In the 22nd century, this technology was used on Earth starships such as the and the  and on smaller auxiliary vessels such as the shuttlepods. During the months the Enterprise was in the Delphic Expanse, polarization technology on Earth had been improved by 12%. (Star Trek: Enterprise; )

In the 24th century, starships still occasionally polarized their hull plating, though not typically as a defensive countermeasure. One example was disrupting a tractor beam lock by rotating the frequency of the hull plating's electromagnetic field. Ships also sometimes polarized their hull plating to help mask their sensory signature, which worked by interfering with enemy sensor scans. Polarizing the hull was also done by downed vessels to help their mothership locate them. 

In 2373, Garak suggested that Worf repolarize their runabout's hull to free them from a Jem'Hadar fighter's tractor beam. 

In 2375, Tom Paris attempted to polarize the Delta Flyers hull after it had crash-landed in order to make it easier for the USS Voyagers sensors to find them. 

In 2376, Voyager's hull was polarized in order to mask their approach towards the errant USS Equinox.