Warring States Period(475-221 BC). Diameter: 3.2 cm, inner aperture: 1.1 cm, thickness: 0.3 cm, diameter: 5 cm, inner aperture: 2.4 to 2.6 cm, thickness: 0.35 cm. Unearthed from the Tomb of Marquis Yi of Zeng at Leigudun, Suizhou,1978.