100ml Round bottom wide neck boiling flask made of high quality Borosilicate 3.3 glass Inside diameter of wide mouth is 1 -1/8" (28.58 mm) Diameter of flask is approx. 2 3/8" (60.3mm) Thick Beaded Rim Clamp Not included - Used for holding imaging purposes It can be purchased by searching PRCMP08BH 100ml Round bottom wide neck boiling flask made of high quality Borosilicate 3.3 glass. Inside diameter of wide mouth is 1 -1/8" (28.58 mm) . Diameter of flask is approx. 2 3/8" (60.3mm). Thick Beaded Rim. Clamp Not included - Used for holding imaging purposes. This clamp can be purchased by searching PRCMP08BH. Eisco Labs Borosilicate glass has the following heat tolerances: Strain Point -515°C | Annealing Point 565°C | Softening Point 820°C.