Remote Switch for Vector computer. 43cm black wire. Optional. Not included in computer kits.  The remote switch (optional, sold separately) is required to access lap timer and rally mode Vector extended feature sets. If not in lap timer or rally mode, the remote switch buttons function as duplicates of the buttons on the main computer.  Lap timer mode is designed for race riders and time trials. Hit the lap counter button each time around the track -- compare lap times on the fly with pace lights, or wait and review precise lap information afterwards. Remote switch required for lap timer mode.  Rally mode is for rally and enduro racing, which requires the rider to be able to adjust the trip distance meter quickly and easily. During rally mode, edit the adjustable distance meter up or down with the remote switch, while the main computer buttons function normally. Remote switch required for rally mode.