These borosilicate glass 4-neck reaction vessel lids/covers have a contact surface that is finely ground to provide a tight seal. Featuring a flat flange, these pressed lids have a center neck and three side necks with outer Standard Taper joints. Use LG-7316 clamps. NOTE: LG-8081 for use with LG-8080 cylindrical reaction vessels. LG-8083 for use with LG-8082 vessels. Scientists rely on the expertise and artistic skills of Wilmad-LabGlass' engineers and glass specialists to manufacture NMR and EPR consumables and laboratory glassware of the highest quality. Used daily in academia, healthcare and chemical, petroleum and other industrial applications, Wilmad offers 7000+ items as part of their standard catalog as well as custom fabrication for individual glassware, glass repair services and OEM glass parts.