Abstract: An optical fiber unit consists of one or more optical fibers configured to provide an optical function, a preformed internal protective body having a preformed space into which the fiber(s) extend with a relatively close fit, the internal protective body being of a material of hardness and coefficient of thermal expansion substantially matched to that of the fiber(s) and the fiber(s) being bonded thereto, an outer protective body surrounding the internal protective body, at least a portion of the outer protective body having a preformed recess shaped to receive and support the rigid internal protective body, a mass of relatively soft uniting material disposed in a manner to secure the internal protective body to the preformed portion of the outer protective body, an injection-molded portion of the outer protective body, of substance less brittle than the internal protective body, effectively surrounding and protecting the internal protective body and the fiber(s) therewithin from the environment in which the