Proline Series 1/4-in x 1/4-in Compression Coupling Union Fitting in the Brass Fittings department at Lowes.com
Stainless Steel Compression Fitting Male Connectors - 1/4"T x 1/4"NPT
Amazon.com: 304 Stainless Steel Compression Fitting Ferrule, 1/4" Tube OD x 1/4" NPT,3/8" Tube OD x 1/4" NPT,3/8" Tube OD x 1/2" NPT Male, Straight Adapter Connect with Ferrules (NPT1/4-1/2"OD) : Industrial
PEEK Two-Piece Fitting w/ Ferrule, 1/4-28, for 1/16" OD Tubing (55301X) - Analytical Sales and Services, Inc.
Flangeless PEEK Fittings + ETFE Ferrules 1/4-28 to 1/16" OD (pack of 1– Darwin Microfluidics
100pcs 1/4 Inch Tube OD Brass Compression Sleeves Ferrules Brass Ferrule Fitting | eBay
5 Pack 1/4" Compression Nut & Ferrule Combo for 1/4" OD Tube Brass Sle – compressor-source
Amazon.com: Beduan 304 Stainless Steel Compression Fitting Ferrule, 1/4" Tube OD x 1/4" NPT Male, Straight Adapter Connect with Double Ferrules : Industrial & Scientific
Megairon 1/4" NPT Male x 14MM Double Ferrule Compression Tube Fitting,Stainless Steel SS304 Male Straight Adapter - Amazon.com