LTWFITTING 1/8 in. O.D. Comp x 1/8 in. MIP Brass Compression Adapter Fitting (5-Pack) HF682205 - The Home Depot
3/4 in. Tube OD - Nut-Ferrule Single Set - 316 Stainless Steel Compression Fitting (1 Nut, 1 FF, 1 BF)
4 Pcs 3/8'' OD Compression Union Brass Compression Tube Fitting 3/8'' OD Compression Tube Connector Use with Copper, Aluminum, Plastic Tubing
Metalwork 304 Stainless Steel Metric Compression Tube Fitting, Male Connector, Adapter, 1/2 NPT Male x 10mm OD (2 Pcs)