Bulb Size and Bases. C7 bulbs are smaller than C9 bulbs by 1 inch. C7 bulbs are 2 inches long and C9 bulbs are 3 inches long. C7 bulbs sit in a base known as a candelabra base and can only fit in this specific type of base. C9 bulbs sit in a base known as an intermediate base.
Indoor cable. Indoor fiber optic cable normally includes tight buffer type, distribution cable, breakout cable and armored cable etc. Cable's job is to protect the fibers from the environment encountered in an installation.
Optical fibres are used to carry signals in the form of pulses of light over distances up to 50km. fibre optic cable is made from a glass core (or in cheaper lower grade ones-plastic) , that carries the light, surrounded by a glass cladding of lower refractive index, which reflects escaping light back into the core.