20mm Flip Off Caps Burr-Free Flip Top Aluminum-Plastic Caps Single Tone Flip Top Seals for Glass Vial 100 Pcs (20mm, White)

These are perfect, but I wish they weren't necessary. If you have vials to seal, these are better than the ones that rip on their own. As the picture shows, the aluminum does not rip at all, leading to no sharp edges. If you are preparing sterile solutions, these are a must-have over the ones that rip themselves off. Note, however, that they are only the caps. No butyl stopper nor vial. You must get those separately.

These sort of items are notorious for not begin precise to either photos or per any sort of specification. 1) the photo shows a 4-tab 'melted plastic fit top' for lack of a better way to describe. They have a 6 tab top which, if they were 'easy' to flip like commercial vials, I would not complain but they are *hard* to flip off leading to perhaps accidental removal of the entire lid. 2) The 'skirt' is the metal aluminum ring on the top. And they are short according to specs (and other tops on Amazon) by about 10 mils. Why the fuss? If you don't do a perfect job of stopper compression and crimping this yields a weak seal which will avulse when popping the hard-to-remove-top (see #1) . These items appear overly critical perhaps but what preventable failure rate do you want on your vials. Failure of this sort should be zero. I had one failure of cracked glass because of need for excessive compressive force to make up for the short cap skirt. Caused grief and loss of almost a day's time plus the embarrassment and stress to speedily get a new vial to a client. The red ones seemed to have this short skirt problem but that is just my experience.

these can only barely crimp over the lip of a 10 or 30ml vial, must apply too much force. was snapping tops off vials trying for a good bite. avoid this brand

These are perfect for re-capping my beauty blends for hygienic use. Now I don't have to dump the whole thing into my Hyaluronic Acid serum and then toss out what I don't use after 30 days. Instead, I can draw out just enough for a day or a week and put the rest in the refrigerator, or portion it out a week at a time. After adjusting a standard crimping tool a bit, I got these to go on nice and firmly. Ordered more. I hope I get purple this time!

very nice and clean after removing the cap .. wish they had gray and clear