The Roman shield was called a Scutum which is the Latin word for shield. The shape of the Roman shield was rectangular and semi cylindrical. This curved shape would protect the Roman soldiers in the front and sides. Roman shields were used by the Roman Army to deflect missiles targeted at the soldiers, as well as protect them from the impact of hand held weapons yielded at them. As time went on Roman shields took more of an oval flat shape.
Historical Clothing Realm carries several full sized and functional Roman shields. Most of our Roman shields have a boss in the center with intricate designs coming from it.
The Scutum shield is light enough to be held in one hand and its large height and width covered the entire wielder, making him very unlikely to get hit by missile fire and in hand-to-hand combat. The metal boss in the center of the shield also makes it an auxiliary punching weapon as well.