Stoppers fit tightly to prevent chemical leaks. Our 5 mm glass tubing fits in the one- or two-hole rubber stoppers. For small test tubes use #00 stoppers. Use #0 for large test tubes, and #1 for extra large. Use #6.5 stoppers for 250 ml flasks. Use a cork borer to drill holes in the corks.
Use our quick & easy guide to identify the size of stopper you need.
Save when you buy 10 or more of one of these stoppers!