Microcarrier spinner flasks promote optimal growth of suspension and microcarrier cultures. Indented bottoms, 100mL thru 1000mL, prevent accumulation of microcarrier beads under the impeller paddle. Please Note: The 6L & 8L Versions Do Not Have Dimpled Bottoms. The complete system includes a flask with two angled sidearms and a PTFE paddle with glass shaft that adjusts trough the compression fitting in the cap.