JACO 15-6-4-P-PG Polypropylene Reducing Union 3/8 OD Tube x 1/4 OD Tube - Single. JACO Polypropylene Reducing Union 3/8 OD Tube x 1/4 OD Tube JACO polypropylene fittings have good chemical resistance and are unaffected by most weak acids and alkalies. Below 175F they have good resistance to organic solvents.They should not be used with oxidants or strong acids or in continuous sunlight. The polypropylene used in JACO fittings is 20% glass filled for improved stiffness and is NSF listed. Connections: 3/8 OD tube x 1/4 OD Tube Fitting Material: polypropylene Ferrule nut with plastic gripper for use with plastic tubing Ferrule nut thread size: 5/8-20 Ferrule nut thread size: 7/16-20 Max Pressure: 220 psi Temperature Range: -30 - 215 F Color: opaque white Advantages of JACO fittings over metal compression fittings: Good electrical insulating qualities. This eliminates the electrolytic action that corrodes tubing caused by a dissimilar metal meeting a fitting. Low density and softness of plastic gives JACO fittings the ability to absorb mechanical and acoustical vibrations. Low resistance to flow due to the smooth internal surface of the fittings. Resistance to scale buildup. JACO Reducing Unions With Plastic Gripper Nut Polypropylene