Illusory Concealable Vest:

The wearer of this concealable vest gains a +1 to +3 enchantment bonus to Defense. Upon command, the protective garment changes shape and form to assume the appearance of a sweater or other normal piece of clothing. The vest retains all its properties (including weight) when its illusion ability is in effect. Only a true seeing spell reveals the true nature of the armor.
Type: Armor (magic); Caster Level: 10th; Purchase DC: 31 (+1), 36 (+2), 41 (+3); Weight: 4 lb.