Brake cables for bicycles are formed or two separate parts, inners and outers. The inner cable moves inside the outer initiating the braking force. We sell inners and outers separately as well as together in a set.
Campagnolo, SRAM and Shimano cables are optimized for use with their own respective levers, so do check before you buy. Most are sold in a standard length which can then be cut to an exact length once fitted.
We like to use products from Shimano and Clarks in our workshops.