Engravable: Why not engrave the name of the deployed? (We do not engrave)
Deploying? Give a token of comfort and encourage the one you love when you are away or deployed. How about the other way around? Give this to the military member! I can tell you after ten years in the Corps, this would have been a cherished gift from the right person.
What is a challenge coin? A challenge coin is a small coin or medallion (usually military), bearing an organizations insignia or emblem and carried by the organization’s members. Traditionally, they are given to prove membership when challenged and to enhance morale. In addition, they are also collected by service members. In practice, challenge coins are normally presented by unit commanders in recognition of special achievement by a member of the unit.