Perfect for creating yeast starters from yeast close to it's best before date or building up yeast numbers for bigger batches. Simply add your starter wort and boil right in the flask using a flat top stove or microwave. These are made from borosilicate glass so they can go from boiling right into a cool water bath to cool down the wort without risk of thermal cracking.
The following sizes are currently available:
1000 mL (1 3/4 inch opening)
2000 mL (1 3/4 inch opening)
3000 mL (1 3/4 inch opening)
5000 mL (2 1/2 inch opening)