30ml Amber Reagent BottleNarrow Mouth with Acid Proof Polypropylene stopper, socket size 34/35Made of high quality borosilicate GlassSize labeled in white on outside of the glassConvenient blank white painted spot to write contents or dates on 30ml Amber Reagent Bottle Narrow Mouth with Acid Proof Polypropylene stopper, socket size 34/35 Made of high quality borosilicate Glass Size labeled in white on outside of the glass Convenient blank white painted spot to write contents or dates on Eisco Labs 30 ml Amber Reagent Bottle , Narrow Mouth with Acid Proof Polypropylene stopper, socket size 14/23 Eisco Labs Borosilicate glass has the following heat tolerances: Strain Point -515°C | Annealing Point 565°C | Softening Point 820°C.