Flask, Boiling RB Heavy Duty 2000ml 24/40 joint. Well crafted with a sturdy joint these round bottom flasks, are made from durable borosilicate glass. The flask you see in the picture is precisely what you receive. These flasks are great for boiling and reactions in the lab. Sold by the each, they are brand new. Texas Residents: Under Texas State Law, this product requires a Precursor Chemical/Laboratory Apparatus NAR-120 permit to ship to a Texas address. After purchase, the seller will contact you via email to verify your permit. Failure to provide a valid permit will result in a cancellation and refund of your order.