Plastic Test Tube Rack for 15/18 mm Tubes, Hole Diameter is 18.7mm, Holds 50, Detachable, Karter Scientific 208U2 (Pack of 1)

I got this to use for holding test tubes for my aquarium API tests. It works great. There are no instructions but basically, you just slide the racks into the little stands. The backside of the shelves have 2 little clear dots to stop from sliding too far. Once I got the first one on (the bottom rack), the others were easy. I did put a drop of cooking oil on the stand where you slide it on, as they wanted to hang up. And one I had to slide back and forth a few times until it would slide on easily. You just have to remember to put the side without the clear dots (stoopers?) in first. It's not real sturdy, but plenty enough for holding test tubes. Well worth the $6.49 I paid. It is larger than I need, but it will make the process so much easier. I guess if you wanted it a little more sturdy you could put a drop of glue on the stands. But not necessary at all. They hold well, even when carrying empty. I wouldn't carry it full of test tubes.

This isn't a hardy product but it is good enough for shelf storage and a very good value at its price. The plastic is somewhat brittle but plenty strong to occassionaly move around. Easy to assemble.

I used itto take daffodils to a flower show, itworked wonderfully.

I bought this test tube rack for holding ink samples from Goulet Pen's Ink Drop program. I like that it holds 50 samples instead of the 40 that Goulet's model holds, and honestly, I'd have to guess that the same manufacturer makes both models. Because there are five rows per column and because each drop contains five samples, too, it's super easy with this rack to organize your samples by month. I love that!Some criticisms of this model claim that it falls apart easily if you try to move it, but I've found that that's not really the case for me, especially if there are tubes in any of the slots. Because the tubes actually go through the holes in the first and second layers, a tube acts as a sort of "pin" holding both layers together. The fit of each layer into the slots of its holders, too, is quite snug and not likely to come loose. I can pick my model up and wave it around all day long without it coming apart. However, if your fittings are lose, a small tab of glue on the open ends of each slot can lock the inserts into place permanently. For the price, I find just a wee bit of DIY totally acceptable for using this thing to its fullest potential, but hey--for $6, I'm happy the thing will just sit still on my desk without falling apart. Plus it looks nice.I do wish the manufacturer would include slots on the top of each side holder and pegs on the bottom, placing them so they interlock if stacked. I think there's actually enough clearance on the bottom of this unit that I could stack them on top of my ink samples, if only the one on top could be secured so it doesn't slide around. And the quality control on these clearly isn't all that great. My unit arrived with a tiny crack in the bottom shelf and slight irregularities in the slits that made assembling the thing a little tricky. Had it gone the opposite way, with irregularities that made the thing too loose instead of too tight, I can see how that could let the shelves slide out too easily. Again, though--$6.All in all, a wonderful solution for storing sample ink vials. I like it and would recommend it especially to those who keep lots of samples on hand or are subscribers to the Ink Drop program.

These are perfect for chocolate dipped pretzels! They are durable, easy to assemble and easy to clean.

TO HOLD BLOOD SPECIMEN TUBES! EXCELLENT!

I ordered the 18.7mm hole size rack after being thrilled with the 18.7mm hole size one that I purchased back in July from the same listing. When this one showed up today the holes are more like 17mm. I can't use it for the intended purpose but I have another purpose I can use it for so I'm keeping it, but please be aware that you might not get the hole size you think you are. It's easy to put together and sturdy - but the one that arrived today is the wrong hole size and now I have to figure out how to get the correct hole size, likely from another source - "fool me once..." and all that.

Excellent sample tube rack at a terrific price!