Heart of America VTX Pit Switch
The Heart of America Pit Switch is a tiny device that allows you to use commands from your flight controller to turn power on and off to an accessory. Designed as a tool for controlling the power to your vtx for team racing. Also great for practice, allow you to power up multiple quads and fly them back to back. The input voltage is good from 5v to 35v and up to 1A.
See this post on setup instructions: HOA VTX pit switch
View the full manual at: http://manual.heartofamericafpv.com