Liquid Tight Flexible Metal Conduit in External appearance Looks like its close relative, Liquid Tight Non Metallic Flexible Conduit. Both have smooth grey outer coats that are liquid tight. Type LFMC comes with an interior steel armor, making it more powerful and less vulnerable to kinking. Both of those raceways can be shaped in soft curves to alter to avoid barriers. In addition, the versatility is helpful for terminating at engines where there's very likely to be heavy vibration.
Liquid Tight Conduit is defined as a raceway of a circular cross-section having an outer liquid-tight, nonmetallic, sunlight-resistant jacket over an inner flexible metal sheath with associated couplings, connectors, and fittings for the installation of electric conductors.
Liquid Tight Flexible Metal Conduit is permitted to be used in exposed or concealed locations where flexibility or protection from liquids, vapors or solids is required. It is permitted in specified hazardous (classified) locations and it may be used for direct burial where listed and marked for the purpose.
If LFMC is used to minimize vibration to or provide flexibility for moving equipment, an equipment-grounding conductor must be provided. Otherwise, the inner metal sheath will suffice.