40V18 - Tweco 40V18 Conduit Liner for ST-21M MIG Gun, 10ft, .035-1/16"

Restore Smooth Wire Feeding

Is your MIG gun sputtering or feeding erratically? Often, the culprit isn't the machine or the drive rolls—it's a dirty or worn-out liner. The Tweco 40V18 Conduit Liner is the genuine replacement part you need to get your ST-21M MIG gun back to peak performance. Designed specifically for the 10-foot ST-21M torch, this liner provides a smooth, low-friction path for your welding wire, ensuring that the wire hits the puddle exactly when you need it to.

Versatile Wire Compatibility

Whether you are running standard .035" solid wire for general fabrication or stepping up to 1/16" flux-cored wire for heavier penetration, this liner handles it all. Its internal diameter is precision-engineered to support this range of sizes without allowing the wire to buckle or bind inside the cable. This flexibility makes it an excellent stock item for shops that switch between different wire sizes and processes using the same gun platform.

Built for the Shop Environment

Welding environments are tough, and your equipment needs to be tougher. The 40V18 features a durable steel coil construction that resists kinking even when the gun cable is bent during tight-access welding. A healthy liner is the unsung hero of a stable arc; by reducing drag on the wire, it reduces the load on your wire feeder motor and helps prevent the dreaded "birdnesting" at the drive rolls.

Easy Installation

Don't let a $20 part ruin a day's worth of welding. Swapping out your liner is one of the easiest and most effective maintenance tasks you can perform. Simply trim to fit if necessary (though it comes sized for 10ft guns), install it into the back of your ST-21M, and you're ready to burn wire. Keep a spare 40V18 in your toolbox so you're never caught off guard by feeding issues in the middle of a critical job.