Collar of Beast Armor 2014
Wondrous Item, uncommon, (requires attunement)
This worked leather collar has stitching in the shapes of various animals. While a beast wears this collar, its base AC becomes 13 + its Dexterity modifier. It has no effect if the beast's base AC is already 13 or higher. This collar affects only beasts, which can include a creature affected by the polymorph spell or a druid assuming a beast form using Wild Shape.
Source: Vault of Magic (Kobold Press) · License: OPEN GAME LICENSE Version 1.0a details