Whilst the Borg do not use shielding as a primary means of defense, Borg vessels do possess shielding for the purposes of propulsion, internal security and as a second line of defense - adaptation. All phasers are generated on a particular subspace phase compression pulse frequency, whilst torpedo warheads all possess their own shielding which also possesses its own subspace phase compression pulse frequency. Adaptive Shielding works by remodulating the shields to the identical subspace compression pulse frequency of torpedos and phasers (Star Trek Destiny - Gods of Night). This is achieved in two basic steps - the shield matrix generates an extremely low power force-field around the exterior of the Borg vessel which samples each particle beam and torpedo frequency which passes through. This data is recorded by the Adaptive Shield Matrix which records and remodulates the vessels primary shield grid to the matching subspace phase compression pulse frequency of the opponents weapons, allowing Borg vessels and stations to become immune to that particular range of subspace phase compression pulse frequencies. Remodulation to a particular phase compression pulse frequency however leaves the vessel vulnerable to the other phase compression pulse frequencies.
-also receives constant frequency readings of enemy vessels from the holding beam, allowing instantanious adaption and remodulation.