Hillman 6-Pack 5/16-in x 1/4-in Threaded Coupling Adapter Fitting in the Brass Fittings department at Lowes.com
5/16"-24 to 1/4"-20 Polisher Buffer Backing Plate Adapter – Tool Guy Republic
5/16" Male Hex x 1/4" Male Square Adapter - BADT3 | Mac Tools
R410A Adapter - 1/4" to 5/16" SAESenville
R410a Adapter for Mini Split HVAC System 5/16" Female SEA x 1/4" Male - BlueStarsParts
Air Conditioning Adapters 1/4 5/16 | Air Conditioning Hose R410a - Vacuum Pump - Aliexpress
LTWFITTING 5/16 in. O.D. Comp x 1/4 in. MIP Brass Compression Adapter Fitting (5-Pack) HF685405 - The Home Depot
PIONEER, CONVERTER ADAPTER, VALVE FOR CHARGING / VACUUMING PORT, FROM 5/16 TO 1/4 INCH SAE » Cedars HVAC
R410A Adapter - 1/4" to 5/16" SAESenville
Amazon.com: R410A Adapter 5/16" SAE Female Quick Couplers to 1/4" SAE Male Flare, 2 PC 45 Degree Angled Charging Vacuum Adapter, Used for R410a with Thimble Mini Split System, HVAC and Refrigeration
Alpine AHMSA1 Adapter 5/16" x 1/4" for Ductless Mini-Split Systems