2-96. Brigades, regiments, and groups are higher echelons than battalions. A brigade is a unit consisting of two or more battalions and a headquarters company or detachment. A brigade normally contains between 2,500 and 5,000 Soldiers. Its capacity for independent action varies by its type. Division commanders use armored, infantry, or Stryker BCTs, supported by multifunctional support brigades (including field artillery brigades, combat aviation brigades, maneuver enhancement brigades, and sustainment brigades) and functional brigades (including air and missile defense brigades, engineer brigades, civil affairs brigades, and military police brigades) to accomplish their missions. All types of brigades and BCTs can task-organize by the attachment or detachment of outside organizations to become brigade task forces.