Description: High quality laboratory stoppers. Best suitable thickness. Can be used on test tubes, flasks, bottles of chemicals, and distillations. Can be used for a wide range of beverages including wine, spirits, olive oil, and a wide variety of gourmet foods products (sauces, marinades, etc). Silicone rubber stopper has excellent heat resistance, cold resistance, dielectric resistance, ozone resistance, resistance to ageing property and excellent physiological inertia air, non-toxic, tasteless, non corrosive, anticoagulant, and body compatibility is good, can be subjected to harsh conditions of disinfection. Specification: Materials: silicone Size Chart: #1 Top Diameter: Approx.25mm/0.98'' Bottom Diameter: Approx. 21mm/0.83 Height: Approx. 45mm/1.77 Suits for flask or test tube that diameter of 21-25mm/0.83''-0.98'' #2: Top Diameter: Approx.28mm/1.1'' Bottom Diameter: Approx. 24mm/1.94'' Height: Approx. 41mm/1.6'' Suits for flask or test tube that diameter of 24-28mm/1.1''- 1.94'' #3: Top Diameter: Approx.31mm/1.22'' Bottom Diameter: Approx. 27mm/1.06'' Height: Approx. 41mm/1.6'' Suits for flask or test tube that diameter of 27-31mm/1.06''- 1.22'' #4 Top Diameter: Approx.34mm/1.34'' Bottom Diameter: Approx. 30mm/1.18'' Height: Approx. 41mm/1.6'' Suits for flask or test tube that diameter of 30-34mm/1.18''-1.34'' #5 Top Diameter: Approx.:38mm/1.5'' Bottom Diameter: Approx. 33mm/1.3'' Height: Approx. 43mm/1.69'' Suits for flask or test tube that diameter of 33-38mm/1.3''- 1.5'' #6 Top Diameter: Approx.41mm/1.61'' Bottom Diameter: Approx. 37mm/1.46'' Height: Approx. 44mm/1.73'' Suits for flask or test tube that diameter of 37-41mm/1.46''- 1.46'' #7 Top Diameter: Approx.45mm/1.77'' Bottom Diameter: Approx. 40mm/1.57'' Height: Approx. 47mm/1.85'' Suits for flask or test tube that diameter of 40-45mm/1.57''-1.77'' Package Includes: 5 Pieces Flask Bottle Stopper