This 2 piece screw & marble terp bead set from Pulsar includes a large marble carb cap and a screw style flow bead that is perfect for use with the Terp Slurp Banger. Terp marbles assist by stirring concentrates via airflow and regulating airflow as a marble cap. Multiple colour options available. Marble set approximate sizes are 23.75mm marble diameter & 26mm x 14mm screw dimensions.