Excellent impact resistance and clarity. The 2L and 2.5L sizes are ideal for use as culture vessels for batch, suspension, or roller culturing. The 3.8L and 8L sizes have shoulder loop for attaching identification tags. Not recommended for vacuum applications. With polypropylene screw closures. Leakproof. Autoclavable. For replacement closures, seeseries. Note: Before autoclaving, set closure on top of bottle without engaging threads.