These oxygen absorbing beer bottle caps change from white to blue when your beer gets cold. The color will begin changing at 46.4 degrees and at 41 degrees they are at their maximum blue tonality indication. They feature a special liner that absorbs oxygen in the bottle head space. This will help reduce the oxidation that happens during the bottling process, keeping your home brewed beer tasting fresher while extending the shelf life.
These caps work with standard pry off glass beer bottles, any size.