Kimax Borosilicate Glass Class A Heavy-Duty Wide Mouth Volumetric Flask with Glass Stopper - 5ml Capacity, ±0.08ml Tolerance (Pack of 6) - Ideal for Chemistry Labs, Scientific Experiments & Precise Liquid Measurements

I bought these to replace some narrower volumetric flasks we use in our lab. The wider mouth decreases the official accuracy of the reading, but it makes filtering into them much easier. Our glass filter funnels have more clearance, so we don't get an accidental seal from a drop of water between the funnel and the flask neck. The glass is heavier too, so they seem less likely to break.