These 3-pin spacer cables are used in line with 3 wire light system.  They allow you to jump from one point to another to continue the same run in two different locations.  Spacer cables connect end to end in series, but it's not recommended to exceed 17 ft total in a single jump, or the data signal could be lost before it reaches the next pebble/light.  Spacer cables come in black.  Lengths can be purchased in 10 ft, 5 ft, or 2 ft sections.