Cap Assembly, Fits Bottles with a 38 mm Cap. The Screw Ring is made of Polypro and has a Stainless Steel Band to keep the Polypro screw ring from stretching. This cap assembly has a center that is made of hi temperature polypro material. The center has 2 each 1/8 inch NPT holes for 1/8 NPT fittings. It includes 2 each fittings for 1/8 inch tubes. Includes an EP Gasket. This cap is designed to fit onto the 4 liter and 2 liter bottles that many solvents are sold in.