Review on Leak-Proof Screw Cap Glass Test Tubes Set of 6, 85mm Length with 5 ml Marking, Perfect for Aquarium Water Tests - Tililly Concepts by Sheila Gray

The screw on the tubes does the trick, preventing spills and leaks when you need to shake the tubes, an improvement over standard API tubes. there are some disadvantages.1. The hole is too narrow. The hole is much narrower compared to API holes, which means you are more likely to miss drops. Cleaning is also a hassle as the tension of the water combined with the narrow opening prevents water from squirting out when you turn the tube upside down, great when you use it but not so much when you want to clean it. The construction screw can break the top half of the tube. This has only happened to me with one of the hoses, but if you overtighten or overtighten, the hose will burst. It could have been user error or broken glass, but I'm pretty sure I didn't use more force than was necessary. All in all a good concept. Could use some improvements.