The Wine-Stone™ at the end of the extended tube is not really a stone but a valve. It is a specially formulated perforated and processed, pure 18-10 stainless steel module that refines the air pumped in into very tiny bubbles. The valve is food safe and free from the possibility of oxidation, corrosion, rust, stain, odor or coloration. To use with bottle, insert the Wine-Stone™ into the wine bottle. Pump ever so slowly no more than 2 or 3 times.