Arduino Mega Sensor Shield v2.0

The Arduino MEGA has many more I/O pins (54 Digital pins and 16 Analog pins)than a standard Arduino. This shield also has connectors specifically for some external devices like an SD Card, Radio communications (Bluetooth and others). It also has an option to power the "V" pins on all the Digital I/O 3-pin groups from an external power supply instead of the Arduino +5V. This is good for large numbers of servos etc. The "Analog" 3-pin groups still use the Arduino +5V which is better from an electrical noise perspective.
This version has two options of +5V supply to all the "V" pins:
Jumper on: +5 comes from the Arduino. Should be limited to about 300 ma
Jumper off: +5 (or other appropriate voltage) comes from an external supply connected to the blue terminal strip. External power Ground must also be connected to the blue terminal strip.

Using an external supply allows more current than the Arduino or Mega can supply, such as current for control of many servos or relays, and other attached devices. Usually this is +5V because most external devices require it. It is possible to use +6 volts if ALL the attached devices are the same such as Servos with that rating.