A sheathed cable refers to a single-core or multi-core wire with a sheath. The sheathed cable is safer. The most commonly used "sheathed wire" is a white PVC sheath with several BV wires inside. This kind of wire is generally a copper core wire. In addition to the insulating layer on the outside of the wire, there is also a protective layer on the outside of the wire.

Commonly used sheath wires are RVV, BVV, RVVB, bvvb these types
v-PVC insulated sheath
v-PVC sheath
R-soft
Copper conductor omitted
VV-PVC insulated poly, vinyl chloride sheathed power cable
RVV-PVC insulated, PVC sheathed flexible cable (also called sheathed wire)
BVVB copper core PVC insulated, PVC sheathed flat cable

The sheath line can be divided into two types: hard sheath line and soft sheath line. According to the application environment and shape, it is divided into round sheathed wire and flat sheathed wire. The round sheath wire is generally multi-core, and the flat wire is generally single-core.
Polyethylene insulated and PVC sheathed telephone lines for telecommunication equipment: HJYVB type and HJYV type are used for telephone connection and audio signal transmission.
Polyethylene insulated and PVC sheathed flat telephone connection cord: HYVB type (two cores) and HYVB type (four cores) are used for the connection of telephone base and telephone handle or junction box.

Product Standards
Enterprise standard: Q/JBRE29-2004, enterprise standard Q/JBRE36-2004
Model Name
HJYVB type: Polyethylene insulated, PVC sheathed flat telephone line
HJYV type: polyethylene insulated, PVC sheathed telephone line
HJYVB type: Polyethylene insulated, PVC sheathed flat telephone connection cord