Flexible (corrugated-black) RKLGF pipes are casing pipes designed to protect electrical wires against mechanical damage (the pipe bends under the influence of the force acting on it, but does not break) and against moisture. Flexible (corrugated-black) RKLGF pipes made of LDPE polyethylene (low density polyethylene) are combustible pipes with good dielectric properties in a fairly wide range of temperatures. Thanks to the extremely low water absorption, their dielectric properties do not change when staying in a humid environment.