16x150mm Borosilicate Glass Test Tubes with Cork Stoppers, 23ml Vol, Karter Scientific 201B1 (Pack of 10)

Fully able to heat and shape them just like Pyrex but a little easier!! The only reason these might crack a little easier than some people expect is because they are a little thinner, but that suits my needs better anyway. I find them plenty sturdy yet they are lighter and I had a reason for needing thinner walls. They ARE borosilicate! There are different ratings, like 3.3 Pyrex, which perhaps they are not (I may boil fluids in thicker ones). But they softened and bent (and even fused!) a little easier than thicker and/or 3.3 boro. If they supposedly crack so easily under slight heat how come I haven't cracked ONE after heating dry until finally melting them into sealed ampules like professional labware? These are perfect for what they are. Better than thicker, name brand Pyrex for me because they shield less, certain emissions of what I place inside, and are lighter. And super value. No scratches, nothing. And a free cardboard stand to complete my cardboard mad scientist lab motif. Seriously, even that target of criticism is perfect to hold them for me, to fill, until they are used and sent away individually! I don't drip something on my own stands and have to clean or paint them. If you use corks, use real cork for dry stuff, and feel out shaping some a bit with sandpaper. Even as cork goes it actually fresh and pliable compared to old, crumbling cork! I saved them for other bottles, another free perk! How much more can I get for so little money??

I did not buy these for lab purposes, but in my use case, they are great quality. I did drop one on a concrete floor and it didn't break, so I trust that these are tough borosilicate glass. I also don't see any manufacturing deviation between tubes. They are all identical, if that matters to you.

Shipping was great, did not have any of them break. Clear quality with no visible deformities or warps or bubbles.The only downside is that mine did not come with the quark stoppers. For what I’m using them for, I don’t need them, but the product is not what was advertised. It could be a one time mistake though, but I’m not going to complain to try to get replacements or money back. It’s still a great product!

Not saying it will work for you but I've dropped a few onto concrete slab flooring and haven't had to pick up broken glass yet. Put those to the side as potential hazards but the not having to clean up broken glass cannot be over stressed. Also the cork was of good quality and well trimmed. I should break one just to see how they break before I praise them too much but they have also survived torching and a number of other abuses at this point so well done. Very nice even glass with no visible defects. Everything I want in a test tube.Update : finally broke one. Nice large peaces, not super sharp. Was using it to melt bismuth...

Finally the right size!

Giving them three stars for the fact that they were quick to respond to the issues and offer a refund but,1. They were poorly packaged! One set was stuffed sideways in a single wall box, the others criss cross stacked so that they had pressure points instead of all the same direction. Out of 100 total tubes ordered, 81 arrived safely. Dealing with broken glass throughout the box, took an hour.2. The corks sent were No. 6, NOT the No. 5 pictured. 90% of them didn't fit, so even though they were also refunded, I had to purchase the correct corks from another vendor. Their customer service said they had only one other complaint, not entirely true when you read the reviews, since many mention them breaking when inserting corks. That would be because they are to big!So after some work, and accounting for a loss, I really only needed 75 but ordered the 100 because of the number of complaints about them arriving broken, the tubes themselves are exactly what I expected.

I used them for bud vase vials.

Nice glass test tubes with a great fitted cork

Good quality glass tubes

I got one extra tube and 13 extra corks! I broke the extra tube trying to cork it too hard so I guess I got exactly what was ordered ;)

5 of the glass tubes were defective and the corks doesn't fit. Wasn't properly wrapped or bubblewraped.

Mostly broken

Buen vendedor aún cuando el producto era muy delicado todos los tubos llegaron en perfecto estado y a tiempo. Lo recomiendo 100%