Guest 1/4 x 3/8 R M Ell

The John Guest 1/4" x 3/8" Reducing Male Elbow from Reliance Worldwide Corporation is a compact push-to-connect fitting built to redirect tubing 90 degrees while stepping down between two common line sizes. In residential water treatment, an elbow like this keeps tubing runs tidy behind reverse osmosis units, drinking-water filters, and refrigerator ice maker hookups, where space is tight and clean routing matters as much as a leak-free seal. By combining a direction change and a size reduction in a single body, it removes a junction that would otherwise need two separate fittings.

Molded from durable polypropylene, this fitting joins 1/4" tubing on the push-in side to a 3/8" male iron pipe thread (MIPT) on the threaded side. The collet-and-O-ring design grips the tube automatically the moment it is seated, forming a reliable seal without wrenches, clamps, or soldering. Polypropylene also resists corrosion and will not scale or rust the way metal fittings can over years of contact with treated water, which makes this elbow a favorite among DIY homeowners and professional installers alike when servicing point-of-use systems.

Key Features

• Connection: Tube x MIPT for a quick transition to threaded ports
• Reducing male elbow design changes both direction and line size in one piece
• Lightweight, corrosion-resistant polypropylene construction
• Push-fit assembly seats in seconds with no special tools
• Sized 1/4" tube to 3/8" thread for filtration and RO plumbing
• Fully demountable for clean servicing and reconfiguration

Reducing elbows are essential whenever a manifold or filter housing presents a different port size than your existing tubing. To install, wrap the male thread with PTFE tape and tighten it into the port, then cut the tube square, push it firmly past the collet until it bottoms out, and pull back gently to confirm the grip. A John Guest locking clip can be added for extra security on systems that see vibration or pressure cycling. When it comes time to service the line, simply depress the collet and the tube releases undamaged. For dependable, leak-free connections in water filtration and conditioning setups, this John Guest reducing male elbow is a trusted, space-saving choice.

Because John Guest fittings share a common collet system across the range, this elbow integrates seamlessly with the unions, tees, valves, and plugs you may already be using. That consistency speeds installation and makes future troubleshooting easier, since every connection behaves the same way and releases the same simple way.