Funnels are supplied complete with a flask length glass stopper of the listed size.The main function is to control the rate of chemical reaction,which is usually used as the instrument to make the extraction operation. ● Material:Borosilicate Glass ● Color:Clear ● The top of the plug for the glass ● Single section through door spring and clamp used in glass door ● Sturdy design is excellent for rack work ● Plug features temperature-resistant,chemical-resistant and corrosion-resistant ● Accessories:A3512-2mm/4mm Accessories for Vacuum Adapters with Glass Stopcock;A3525-01/03 Replacement Stainless Steel Retention Kit for Glass Stopcocks