Sparrow Tension Wheel - Available in Black or Brass is a great tool for the kit when properly used. Tips for use: Lock to be mounted or controled such as a vice. Light tension gives it real light tension it is suggested to start in the half bar section and rake the lock. Release the tension, if no pins dropped increase the tension by another half a bar -- if you can hear the tension you are in the correct zone and you may apple the same amount of tension and start your picking!
This tool is also great while teaching a newbie, as tension control can be hard. With the marked tension you can be sure you are using the right amount each time. If you prefer to use electronic lock picks or snap guns this is a great tool to go with it as well!