They're simple to fill and the silicone plug to stopper. Good transparency. Great choice for general-purpose and laboratory use, and widely used in clinical chemistry, molecular biology, bio-chemistry and other experiments and research. Features -Color:Transparent -Material:Silicone, glass -Size:14.50X1.60X1.60cm,3.50X1.80cm/5.70X0.63X0.63in,1.38X0.71in -Test Tube Capacity:16ml -Transparent design: These glass tube are transparent and visible, you can see what is inside the glass test tubes clearly and observed the item you storage in it. - : glass test tubes are resistant to heat, and chemically stable, and they have smooth and flat inner surface, no residual solution. -Large Numbers: Enough quantity glass test tubes with silicone plugs, which are sufficient to meet your daily classroom, laboratory and even home storage. -Seal and Safe: Each glass test tube has a seal silicone plug, used to prevent sample leakage, safe for you to transfer to anywhere you need. -Wide Application: The glass vials tubes are great for professional laboratories and classrooms, also fit for household storage, household laboratories and more. Package list: 60 Tubes 16ml 60 x Silicone Caps