Mage Armor(Player's Handbook v.3.5, p. 249)
Conjuration (Creation) [Force]
Level: Sorcerer 1, Wizard 1, Knight of the Weave 1, Beguiler 1, Sha'ir 1, Court Herald 1, Merchant Prince 1, Bladesinger 1, Force (CD) 1, Spell 1,
Components: V, S, AF,
Casting Time: 1 standard action
Target: Creature touched
Duration: 1 hour/level (D)
Saving Throw: Will negates (harmless)
Spell Resistance: No
An invisible but tangible field of force surrounds the subject of a mage armor spell, providing a +4 armor bonus to AC. Unlike mundane armor, mage armor entails no armor check penalty, arcane spell failure chance, or speed reduction. Since mage armor is made of force, incorporeal creatures can't bypass it the way they do normal armor.
Focus: A piece of cured leather.