• With stem inside cone

Boro 3.3 or Borosilicate 3.3 is a type of glass having very low coefficient of thermal expansion Borosilicate glass 3.3 is highly resistant to water effects, neutral and acid solutions, heavy acids and their mixtures, to chlorine, bromine, iodine and organic compounds. Even in long-term effects and at temperatures above 100 °C, this glass outstrips with its chemical durability most metals and other raw materials. Class of Resistance to Acid Effects (ISO 1776 a DIN 12116) is Class S1. White Printing PTFE Stopcocks regulate the flow of liquids or low pressure gases & serve many functions in the laboratory & has the distinct advantages over glass for use with high vacuum & being much easier to clean due to grease free operation. For liquid applications, it also means that you won't contaminate your reaction mixture with grease. PTFE keys are interchangeable and replaceable so that there is no need for “matching the pairs” during cleaning. PE Stopper With Cone and socket