The gradual impact of inflation caused by debasement of the silver currency meant that the purchasing power of the sestertius and smaller denominations like the dupondius and as was steadily reduced. In the 1st century AD, everyday small change was dominated by the dupondius and "as", but in the 2nd century, as inflation hit, the sestertius became the dominant small change. In the 3rd century silver coinage contained less and less silver, and more and more copper or bronze. By the 260s and 270s the main unit was the double-denarius, the Antoninianus, but by then these small coins were almost all bronze. Although these coins were theoretically worth eight sestertii, the average sestertius was worth far more in plain terms of the metal it contained.