Guest 3/8 Locking Clip

The John Guest 3/8" Locking Clip from Reliance Worldwide Corporation is a simple, inexpensive accessory that locks a push-fit connection in place. It snaps over the collet of a 3/8" John Guest fitting to prevent the tube from accidentally backing out, an easy safeguard against leaks in water treatment plumbing and one of the cheapest forms of insurance you can add to a build.

On a push-to-connect fitting, the collet locks the tube once it is inserted. A locking clip wedges between the collet and the fitting body so the collet cannot be depressed and the tube cannot release. This protection matters most in reverse osmosis and under-sink filtration, where a single dislodged 3/8" line could flood a cabinet before anyone notices, turning a minor oversight into costly water damage.

Why Installers Use Them

• Secures the collet to prevent accidental tube disconnection
• Made from durable, corrosion-resistant polypropylene
• Sized for 3/8" John Guest push-fit fittings
• Snaps on and off by hand, no tools required
• Adds security in RO, filtration, and high-vibration installs
• Reusable, so it can be removed and refitted during service

Installation could not be simpler. After seating your 3/8" tubing fully into a John Guest fitting and confirming the grip with a gentle tug, clip the locking ring around the exposed collet so it sits flush against the fitting body. When you need to service the connection later, pop the clip off, depress the collet, and the tube releases cleanly and undamaged. Once the line is remade, the same clip refits in seconds. Experienced installers add a clip to every connection that carries pressure or sits where a leak would do the most damage. Keep a handful on hand whenever you build or maintain water filtration and conditioning equipment; for the cost, this John Guest locking clip buys a great deal of peace of mind.

Although it costs almost nothing, the locking clip guards against the kind of failure that does the most damage: a 3/8" line releasing under a sink and flooding a cabinet unnoticed. Adding a clip to each pressurized connection is a small step that professional installers take as standard practice, and it gives homeowners servicing their own equipment real confidence that the job will stay leak-free.