Thomas & Betts LTGUS11G-A LFMC GP UL 4IN GRY 8M/25FT

The LTGUS11G-A is a 4 inch liquid tight flexible metallic conduit supplied as a 25 ft (8 m) coil. If you are running a longer pull than 25 feet, you will need multiple coils plus the connectors to join runs at boxes or equipment.

Galvanised steel core with a gray jacket over it. That is the standard LFMC construction: a helically wound galvanized steel strip under a liquid tight outer jacket, so you get physical protection and flexibility in one run rather than the plastic-only construction you'd get from liquid tight flexible nonmetallic conduit.

Large feeder and service-size runs where a rigid raceway will not work: the final connection into a rooftop chiller or large air handler, a motor or generator that vibrates, a transformer secondary, or any equipment that needs to be pulled for service. The flexible steel core absorbs vibration and misalignment, and the jacket keeps water out in wet and outdoor locations. At 4 inch trade size you are typically carrying large feeder conductors, not branch circuits.

Pick the metallic type, like the LTGUS11G-A, when you want the mechanical protection of a galvanised steel core and a raceway that can take physical abuse or vibration at the equipment. Liquid tight flexible nonmetallic (LFNC) is all plastic, lighter, and easier to handle, but it does not give you the crush resistance of a steel core. Both keep liquid out; the difference is the core and how much abuse the run will see.

Do not count on it. Large trade size LFMC generally requires a separate equipment grounding conductor pulled inside the raceway, and the conduit and its fittings are not treated as the ground path at this size. Pull a properly sized EGC with your feeder conductors and bond at both ends.

The LTGUS11G-A is the gray jacket. Jacket color on LFMC is a field and trade convention, not a change to the raceway itself, but if you are matching existing runs on a building or a spec calls out a color, order the gray specifically by the LTGUS11G-A part number rather than by trade size alone.