VWR Rubber Stoppers TW-4 Pack of 40. Combining top-notch and uncompromising quality with an affordable price the VWR Rubber Stoppers TW-4/ 59586-158 can fulfill your laboratory needs while still offering a great value for the money. Product Category Description: Rubber stoppers are essential for weighing and stopping flasks with a standard ground finish. Flat bottoms tend to retain heat generated during the distillation process. Natural rubber is softer than black rubber and tends to float. Stoppers resist acids alkalis and most organic solvents. Graduations are less than one millimeter. Ordering Information: The STEPHENSON stoppers are individually poly bagged. Bags are shipped flat. After opening the stoppers expand to twice their original volume to close the bag. After use the stoppers expand to absorb any remaining moisture. Bags are color-coded with one color-coded top and bottom. The NPTIMEX stoppers are molded of natural rubber. Specifications for VWR Rubber Stoppers TW-4 : Size: 4 (Please note that the description and stock photo may not correspond to the specific model listed above) We offer only genuine Plasticoid 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 Rubber Stoppers TW-4/ 59586-158 we carry a full complement of Laboratory Consumables as well as other product offerings from Plasticoid. 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 Plasticoid 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 Rubber Stoppers TW-4 Pack of 40