Brass Tube Support, 1/4

This 1/4-inch brass tube support from Midland Metal, sometimes called an insert, is a small reinforcing sleeve that slides inside soft or thin-walled tubing to keep it round and prevent collapse when a compression fitting is tightened. By supporting the tube wall from within, it allows the ferrule to grip evenly and form a strong, leak-free connection that stands up to system pressure.

Plastic and poly tubing are convenient and inexpensive, but they can deform, pinch, or partially collapse under the clamping force of a compression nut and ferrule. When that happens, the seal becomes uneven and prone to leaking, and the tube can even pull out under pressure. Inserting a brass tube support into the end of the tubing solves the problem by holding the tube's shape, so the ferrule seals consistently all the way around the circumference. It is a small detail that has an outsized effect on connection reliability.

• Brand: Midland Metal Mfg
• Fitting type: tube support / insert
• Material: brass
• Size: 1/4 inch
• Prevents tubing collapse in compression fittings
• Item weight: 0.01 lbs

For installers and DIY owners working with 1/4-inch poly or soft tubing on reverse osmosis systems, filters, and water treatment accessories, tube supports are an essential companion to compression nuts and sleeves. They are easy to forget until a connection leaks, at which point their value becomes obvious; including them from the start saves rework.

To use, simply press the support fully into the end of the tubing before assembling the compression nut and ferrule, then tighten the fitting to a firm, leak-free joint. Keeping a handful of these inexpensive brass inserts on hand ensures every tubing connection you make is secure, round, and dependable, whether you are building a new system or servicing an existing one. On systems where a tubing connection failure could mean water on the floor or a starved RO membrane, the few cents spent on a proper tube support are among the best-value insurance in the entire fitting kit. A square-cut, deburred tube end paired with the support also helps the connection seat cleanly, so a little care in preparing the tubing goes a long way toward a joint that seals reliably and stays put under pressure.