Perfect size. 18mm(0.7 Inches) in diameter, round shaped with smooth finish.Scratch proof. Hard surface provides the resistance ability on scratch or while using. And the Acrylic is much stronger than a glass sphere or crystal ball.Light weight. 4g in single ball weight, Acrylic sphere is portable (50% lighter than glass) and easy to install as a ornament.Transparent. 92% light transmittance, for visual device like len or as a lab equipment. Furthermore, the acrylic ball has the capability to resist high temp.Multi purpose. Acrylic plastic resin balls could be used as Zoom Equipment (len), Light decoration, crafts project or home ornaments.Solid Round Acrylic Sphere BallDiameter: 18mm/0.7 inchesColor: Clear/TransparentTransmittance:0.