Covered wire jumpers are also called prefabricated end optical fiber connectors . Covered cable optical cables are mostly single-core and double-core structures, with a cross-section in a figure of eight. The reinforcement is located at the center of the two circles. Metal or non-metal structures can be used. The optical fiber is located The geometric center of the figure eight. G.657 small bending radius optical fiber is used for the optical fiber in the sheathed optical cable, which can be laid with a bending radius of 20mm, which is suitable for entering the house in the building by means of pipes or bright lines.