VWR Corks. The stopcock is stamped "Manton Cork" to ensure proper sealing and identification. Stamped "Manton Cork" means that the product meets very stringent ISO standards and is of highest quality. The convenient two-leaf stopcock is stamped "Manton Cork" to clearly state the source of the product. Non-sterile: This product contains a chemical which when in contact with acids will cause the cork to expand and contract causing the sample to expand and collapse. To release the stopcock the outer lip of the cork from the stopper must be turned over. Chemical compatibility: This product can be used with acids alkalis and base metals (except for the top blue variety which are marked Tris). Specifications for VWR Corks 50624 : Number: 6 DiameterTop mm: 19 DiameterBottom mm: 14 Lengthmm: 24 (Please note that the description and stock photo may not correspond to the specific model listed above) We offer only genuine Manton Cork products authorized for sale in the U.S. and other markets so you can be sure that you are buying authentic Laboratory Consumables with a full manufacturer's warranty in addition to our own 100percent Satisfaction Guarantee. We are your premier online distributor for VWR Laboratory Consumables. We are an authorized supplier to all federal and state government agencies as well as to research and educational institutions and can facilitate volume orders on many types of laboratory equipment lab consumables and other products to help fulfill your specific needs. We offer Free Shipping and FREE USPS shipping to APO and FPO addresses on all orders in our store over 49. Please refer to our APO/FPO Shipping and Export Restrictions for more information on export to APO/FPO addresses. In addition to the VWR Corks 50624/ 23420-184 we carry a full complement of Laboratory Consumables as well as other product offerings from Manton Cork. We also carry a full line of VWR accessories to help meet your laboratory and scientific needs. For a complete selection of VWR Laboratory Consumables please visit our Manton Cork page. For more brand name Laboratory Consumables please visit our Laboratory Consumables store section. To see our complete line of lab medical industrial and scientific products please see our science and lab equipment online catalog. VWR Corks 50624