These are Ultra High Flow bulkhead fittings for 3/16" or 1/4" ID tubes. Barbed on both ends.
They have a hex flange and a nut.
Made of nickel plated brass for improved corrosion resistance of the thread.
The thread is 1/8" NPT.
The fitting is 1.3" long.
New! Also offered in "maxiflow" regular size: 3.3 mm ID for 1/8" ID Tygon tubing. This size is 0.2 mm larger in ID than 1/8" to reduce flow turbulence at the fitting.