*PLUMBERSSTOCK EXPERT* responded:
Hello! We are happy to answer your question. Thank you for your interest in our General Aire 1A-25A Fuel Oil Filter. We have acquired information from the manufacturer. You will need a 3/8" x 1/4" reducer. Please click this link to view our wide selection of reducers. If you're done selecting what you need, please click the "Add to Cart" button and you're all set! Thank you and have a great day!