Specification Brand : QuafooLAB BulletPoint1 : 45/50 Joint Hollow glass stopper; BulletPoint2 : Borosilicate Glass, low expansion rate, high strength, high hardness, high temperature resistance and resistance to 200 ℃ temperature difference. BulletPoint3 : High light transmittance, high chemical stability, acid and alkali resistance. BulletPoint4 : Easy to clean and rotate in or out. Grooves in the sides help prevent slippage,Reusable High quality. BulletPoint5 : Use the hollow glass stoppers to seal lab glassware such as flasks, separatory funnels, cylinders. Color : Black ItemName : QuafooLAB Glass Penny Head Glass Hollow Stopper for 45/50 Outer Joint Glass, Borosilicate Glass,with Closed Bottom ItemPackageDimensions_Height : 0.79 inches ItemPackageDimensions_Length : 2.36 inches ItemPackageDimensions_Width : 0.79 inches ItemPackageQuantity : 3 ItemTypeKeyword : science-lab-rubber-stoppers Manufacturer : QuafooLAB Material : Rubber Material1 : Silicone Material2 : Rubber ModelName : rubber stopper ModelNumber : 33x38mm NumberOfBoxes : 1 NumberOfItems : 1 PartNumber : GL0000024 ProductDescription : Silicone Rubber Stoppers Plugs are used to seal bottle flasks in the laboratory or seal holes tubes in the kitchen, home, etc. Specifications: Material: Rubber Color: Black Package Content: 2 x Rubber Stopper Plug