Omsons Round Bottom Culture Tube with Screw CapOmsons round bottom culture tubes with screw cap are used for laboratory sample handling, storage, mixing, and culture work. Made from borosilicate 3. 3 glass, these tubes include screw thread openings, Teflon liners, and PP screw caps for leakproof closure. Key Details Product Type: Round bottom culture tube Glass Type: Borosilicate 3. 3 glass Bottom Style: Round bottom Closure: PP screw cap with Teflon liner Tube Dimensions: Listed by size option