The Neutrocork® Premium stopper is the most recent evolution of the Neutrocork® stopper. It guarantees perfect performance of wines stored for up to 36 months in the bottle. This latest generation stopper uses the patented ROSA High Tech® steam sterilisation system, which is an evolution of the previous ROSA® treatment system. This latest system provides even deeper sterilisation in the cellular structure of cork, eliminating the invasive volatile substances that may potentially be present and maintaining the natural characteristics of cork unchanged, even with micro-granulated products. There is no need to insert any plastic expansion substance.