Corning roller bottles are manufactured from virgin polystyrene and are treated for optimal cell attachment. Bottles feature superior optical clarity and a seamless one-piece durable construction that reduces damage caused by transit and accidental dropping. New easy grip caps are designed for comfortable manual handling featuring half turn on/off seating, smooth round edges and large easy grip knurls. Vent cap 850cm2 bottles have primed graduations every 50ml up to 2000ml; 1750cm2 bottles have printed graduations every 50ml up to 1500ml. All bottles are certified non-pyrogenic and most have indivually printed lot numbers to aid in product traceability. Packaging: 5/pk 20/cs