SRAM's Shift Cable Kit is the right kit to have on hand so you can fix a broken cable and a nice upgrade, too. It comes with 2 1.1mm-diameter SRAM shift cables and enough SRAM 4mm-diameter compression-free housing to fit any size bicycle. The housing has a slippery liner for super-smooth shifting. You also get SRAM aluminum ferrules and cable crimps to prevent fraying.
SRAM's SlickWire MTB Brake Cable Kit is the perfect kit to have on hand to fix broken cables and a great upgrade, too. You get excellent stainless-steel cables, slippery lined 5mm-diameter housings, aluminum ferrules and frame protectors.