If you're looking into the ULAB UTR1009 Stainless Steel Test Tube Rack, it can hold test tubes with a maximum diameter of 25mm. The manufacturer's description mentions it can securely accommodate up to 12 test tubes, and the holes are sized at 27mm to provide a snug fit, ensuring smaller tubes don't slip around.

The rack is made from stainless steel, which means it's pretty tough and resistant to corrosion, making it suitable for various lab environments. It can handle high and low temperatures, as well as exposure to acids and alkalis. Plus, it's safe for freezers and autoclaves, which makes it handy when you need to sterilize it.

According to our research, folks generally find it stable and easy to use. The polished surface helps prevent injuries from sharp edges, which is great for busy labs. However, there was a comment about encountering some sharp edges, so it might be good to inspect it when it arrives just to be sure.

Overall, if you need a reliable rack for organizing your 25mm test tubes, this one seems like a solid option, whether you're in a professional lab or a classroom.