Insignia of the Alliance

Insignia of the Alliance is a quality PvP trinket that removes all movement impairing effects but does not prevent them from being reapplied. Usable even if the effect would normally prevent trinket use.

Source
This item is a quest reward from Hellfire Fortifications (Alliance).

Upgrade
There is an upgraded version, the Medallion of the Alliance, which is available at level 70, has only a 2-minute cooldown, and has a Resilience bonus.