3/8" to 3/8'' Barb Splicer Mender, Stainless Steel Barb Union Fittings. Our 3/8 inch barb fitting adapters are used in a wide range of applications. You can use them to service water softener drain line, dishwasher drain line, heater hoses, radiator output hoses. 3/8'' to 3/8'' fuel line adapter. Replace your old fittings with 3/8'' hose barb fittings, which are made of stainless steel, are durable and can be used for a wide range of media. No matter if you're a car enthusiast, a green-thumb gardener, a hands-on homeowner, or a seasoned pro in the trades, these fittings make a great supplement to your tool collection or workshop.