What is this?The Rubber Tapered Plug is great for laboratory utensils such as flasks, test tubes, or other laboratory applications, also can as a sewer plug, water pipe plug, or drain plug.What will I get?The tapered plug is in size of: Bottom Diameter: 25mm / 0.98 inch; Top Diameter: 33mm / 1.3 inch; Height: 30mm / 1.18 inch; Fit Hole Size: 27-32mm; In the package of: 3 x Rubber Tapered PlugAre there any advantages of the product?Made of Rubber, with good resistance to chemicals, acid and alkali resistance, can withstand high temperatures in a short time.There is a hole in the center of the plug for inserting a glass tube, very convenient for meeting your needs.How to use it?Conical design, solid, easy to install and good sealing performance, flexible and durable, not easy to crack, shrink, harden or break.