Description:Solid Rubber Stopper Dimensions: Diameter 17mm to 23mm, height 26mm, suitable for 19-21mm hole diameter.Durable Material: The drainpipe plugs are made of solid rubber, high density, elastic, good sealing, wear-resistant, not easy to deform, and long-lasting.Tapered Design: These white lab plugs are tapered, and have a smooth surface,  with good sealing and insulation performance.Easy to Use: These silicone lab stoppers are easy to install, just insert the rubber plugs, and gently turn them to ensure that they are in place and firm fit.Application: Our rubber plugs are not only suitable for sink and downspout use but also for laboratory. They can be used to plug glass ports and pipe ports, and can also be used to plug and seal test tubes, containers, and flasks to prevent leakage.