Essence Of The Guard

Essence of the Guard (embedded component): This dull coppery disk bears symbols representing watchfulness. When embedded in a warforged, it occupies space on the body as an amulet, granting the character a +5 competence bonus on Listen and Spot checks.
Faint divination; CL 5th; Craft Wondrous Item, clairaudience/clairvoyance;
Price 6,250 gp.

Source: Races of Eberron