The purpose of this standard is to establish the test methods and specifications for three-piece stoppers, ready for use, used to stopper bottles of still and semi-sparkling wines that comply with the UNE 126403 Standard Glass containers. Mouths. Mouth profile for closure with cork stopper and UNE-EN 12726, Containers and packaging. Mouth for cork stoppers with an inlet diameter of 18.5 mm for safety corks and capsules. This standard applies to stoppers formed by an agglomerate cylinder made of natural cork with a natural cork disc attached to each end.