Stainless Steel Instrumentation Hex Couplings - 1/8" x 1/8"
Pack 1/8" x 1/8" NPT Coupler, Brass Female Pipe 1/8" x 1/8" NPT Female 2 | eBay
USA MADE Foster 2202 1/8" Male NPT X 1/8" Industrial Coupling Air Hose Fittings | eBay
Amazon.com: Single S316 Stainless Steel 1/8 NPT Male to 1/8 NPT Male Straight Hex Coupler/Coupling for Air, Liquid or Hydraulic Fitting - Industrial Air Tool Hose 1/8 Inch Coupling : Industrial & Scientific
Pipe Fittings Direct. 1/8 inch NPT class 150 full coupling Cast 304 Stainless Steel