Penny Head Stopper, Amber, Made With Borosil Borosil® Amber Solid Penny Head Glass Stopper, Interchangeable Ground Joint 12/21 CS/20 Specifications Material: 3.3 Borosilicate Color: Amber Class/Quality Grade: Class A/Type I Dimensions: 136mm(5.35") X 72mm(2.83") X 120mm(4.72") Joint size: 12/21 Documentation Datasheets Coming Soon! Videos Videos Coming Soon! Check out all of our videos on our YouT