Proline Series 3/8-in x 1/4-in Barbed Splicer Adapter Fitting in the Brass Fittings department at Lowes.com
Amazon.com: Pysrych Brass Hose Barb Fitting Reducing Tee 1/4" Barbed x 3/16" Barbed x 1/4" Barbed Reducer T-fitting 2pcs : Industrial & Scientific
Amazon.com: JoyTube Brass Hose Barb reducer 1/4" to 3/16" ID hose Barb Fitting Hex Splicer Mender Union Air Water Fuel Tubing Adapter with hose clamps (Pack of 3) : Industrial & Scientific
2 pcs Brass Tee Barb Fittings 1/4"(6mm), 5/16"(8mm), 3/8"(10mm), 1/2"(12.7mm), 3 Way Tee Connector Adaptor by U.S. Solid - U.S. Solid
LTWFITTING 3/16 in. ID Hose Barb x 1/4 in. MIP Lead Free Brass Adapter Fitting (5-Pack) HFLF39183405 - The Home Depot
LTWFITTING Compression Reducing Union 3/16-Inch OD x 1/4-Inch OD Brass Fitting (Pack of 5) - Amazon.com
Hillman 5-Pack 1/4-in x 3/16-in Threaded Coupling Adapter Fitting in the Brass Fittings department at Lowes.com
Everbilt 3/16 in. Barb x 1/4 in. MIP Brass Adapter Fitting 800109 - The Home Depot
Tylok CBC-LOK Fittings - Reducer Adapter Tube to Tubes Brass