Cole-Parmer VapLock™ Fitting, Polypropylene, Straight, Hose Barb to Threaded Adapter, 5/16" ID x 1/4" NPT(M); 10/PK from Cole-Parmer United Kingdom
Amazon.com: Beduan Brass Hose Barb Reducer, 5/16" to 1/4" Barb Hose ID, Reducing Barb Brabed Fitting Splicer Mender Union Air Water Fuel : Industrial & Scientific
Charging Hose Adaptor 410A. 5/16" Male to 1/4" Female
5/16" Hose Barb x 1/4" Male NPT Brass Adapter Threaded Fitting, Fuel/Water/Air | eBay
Stainless Steel Hose Connector, 1/4 in. Male NPT, 5/16 in. Hose ID | End Connections | Flexible Tubing | Hoses and Flexible Tubing | All Products | Swagelok
2X R410a AC Refrigerant Adapter 5/16 1/4 SAE M F Male Female For Valve System XY | eBay