Durable Nalgene brand. Containers are constructed of polymethylpentene and are clear and autoclavable. Screw on lid.
This is the flask we use in our lab. The extra volume in the 1000ml flasks makes it a lot easier to prepare and pour a standard 500ml nutrient agar run of 20 petri dishes. Our flasks have held up very well to repeated sterilization and exposure to UV light.