LTWFITTING 3/8 in. O.D. x 5/16 in. O.D. Brass Compression Reducing Coupling Fitting (25-Pack) HF62R6525 - The Home Depot
Brass Compression Male Adapters - 5/16" x 3/8"
240DE – 5/16 X 3/8 Female Inverted X Male Inverted Flare – Couplings Company
3/8" to 5/16" Fuel Line Adapter Fitting
Hillman 5-Pack 5/16-in x 3/8-in Threaded Coupling Adapter Fitting in the Brass Fittings department at Lowes.com
3/8" Male NPT x 5/16" Flare (SAE) Brass Adapter
EDGE INDUSTRIAL 3/8" X 5/16" Hose ID Brass Barb Reducer SPLICER Fitting Fuel / AIR / Water / Oil / Gas / WOG (Qty 1): Amazon.com: Industrial & Scientific
Earl's AT165256ERL Earl's 3/8" NPT Male to 5/16" Tubing Adapter
Amazon.com: Brass Hose Barb Reducer, 3/8" to 5/16" Barb Hose ID, Reducing Barb Brabed Fittings Splicer Mender Union Air Gas Water Fuel Line Heater Garden Pond Poly Tubing Adapter (Pack of 2) :
5/16" Compression x 3/8" Female Brass Adapter - Warren Pipe and Supply
1 Brass Brake Line Adapter 3/8" x 5/16" x 1/2" x 20 TPI
Puller Adapter 5/8-18 Female To 3/8-16 Male
Norgren - Push-To-Connect Tube to Male & Tube to Male NPT Tube Fitting: Pneufit Male Adapter, 3/8" Thread, 5/16" OD - 48786750 - MSC Industrial Supply
Midland Metal Mfg. 18204 7/16 X 3/8 (comp X Mip Adapter), Brass Fittings, Compression, Male Adapter | Blackhawk Supply
5/16" Flare x 3/8" Male Brass Adapter - Warren Pipe and Supply
Amazon.com: Beduan Brass Hose Barb Reducer, 3/8" to 5/16" Barb Hose ID, Reducing Barb Brabed Fitting Splicer Mender Union Air Water Fuel : Industrial & Scientific