400021 is a part of the Helukabel cable range, which consists of a wide variety of cables and wires for various applications. The 400021 is a low-voltage cable designed for use in building installations and devices. It comes in a variety of different types of insulation, including PVC, halogen-free, PUR, and unsheathed versions. It is also designed to meet various standards and can be used in a variety of installations, including home automation, industrial automation, and wiring for communications.