I'm currently playing a Gunslinger with a dip in Monk and I'll be taking an unarmored approach to make full use of Wisdom synergy. The Gunman's Duster is a wondrous item worn in the body slot which provides a +4 armor bonus to AC. The Monk's AC bonus class feature says this:
When unarmored and unencumbered, the monk adds his Wisdom bonus (if any) to his AC and his CMD. In addition, a monk gains a +1 bonus to AC and CMD at 4th level. This bonus increases by 1 for every four monk levels thereafter, up to a maximum of +5 at 20th level.
These bonuses to AC apply even against touch attacks or when the monk is flat-footed. He loses these bonuses when he is immobilized or helpless, when he wears any armor, when he carries a shield, or when he carries a medium or heavy load.
Does this item count as armor for the purposes of this class feature?