Type 1 class a Borosilicate glass that are designed for maintaining anaerobic conditions. Useful for studies involving methane-producing bacteria, cell culture, drug discovery, and research and development. MADE IN THE USA.Specifications: Size: 250ml Neck Finish: #20 Alum Seal Neck. Dimensions: 70mm OD x 138mm OAH, Neck Dimensions: 19.7-20.2mm OD, 13.3-13.6mm ID, Grad. Range: 50mL-200mL, every 50mL, Supply with #20 Septum Stopper & Alum Seal.