A 90° elbow fitting that connects a 1/4″ male pipe thread (MNPT) port to 3/8″ OD quick-connect tubing — the cross-size adapter for systems that mix 1/4″ threaded components with 3/8″ tubing. Sold as a 2-pack.

What it does

This elbow connects a 1/4″ MNPT threaded port (on an inline filter, valve, or housing) to 3/8″ OD tubing at a 90-degree angle. The threaded side screws into the port with PTFE tape; the push-fit side accepts 3/8″ OD tubing tool-free.

Use it wherever a system mixes thread sizes — common on under-sink RO setups where the membrane housing or manifold has 1/4″ ports but the main lines run in 3/8″ tubing for higher flow. The elbow keeps the routing tight and eliminates kink-prone bends.

Key benefits

• ✓1/4″ MNPT × 3/8″ OD QC — cross-size thread-to-tube adapter
• ✓90° elbow — space-saving turns in tight installs
• ✓Push-to-connect tube side — tool-free 3/8″ tubing connection
• ✓Bridges 1/4″ threaded ports to 3/8″ tubing lines
• ✓Suitable for under-sink RO, inline filters & water filtration
• ✓2-pack with automatic quantity discounts

Specifications

Compatibility

Often used with

Good to know before you buy

• Wrap the 1/4″ MNPT threads with PTFE tape (2–3 turns clockwise) before threading in.
• Hand-tighten, then snug slightly with a wrench. Do not over-torque.
• Push 3/8″ OD tubing firmly into the quick-connect port until it seats.
• Check all connections for leaks before putting the system into service.