5272K195 Yor-Lok Fitting for Copper Tubing. Straight Adapter for 3/8″ Tube OD x 3/8 NPT Male. These fittings include a nut with two sleeves (ferrules) for extra gripping power. The sleeves bite into tubing as you tighten the nut, creating a strong seal. Also known as instrumentation fittings, they are made to tight tolerances for use in high-precision applications. Fittings are brass for good corrosion resistance. They are compatible with Swagelok®, Let-Lok, and A-Lok fittings.