Labnique Borosilicate 3.3 Glass Conical Flask, Erlenmeyer Flask with Narrow Mouth, Graduated, Double Boxed, 500ml (Pack of 8)

They came in a box with individually packed and in a foamed box for each flask. I have used them for refining and distilling acids and bases up to ~120°C and had no problems with thermal shock, cracking, or any other heat induced problems with a thermal gradient as much as 80° from top to bottom. They hold above their rated capacity so you have a little breathing room if you deal with liquids that expand drastically when heated. If I need flasks again in the future then I would buy from these people again. Pictures above are at just above 100°C with an Iron acetate solution with other components. Always perform refining and distilling in well ventilated areas, and wear propper PPE.

Work well for yeast step starters.