Bottle Reagent, Amber colour, narrow mouth with acid proof polypropylene stopper 30ml., socket size 14/23-EIS-CH0161A offers a thoughtfully designed, durable resource for hands-on learning. 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.