This Ramps shield Smart Controller contains a SD-Card reader, a rotary encoder and a 20 Character x 4 Line LCD display. You can easy connect it to your Ramps board using the "smart adapter" included.
After connecting this panel to your Ramps you don't need your pc any more, the Smart Controller supplies power for your SD card. Further more all actions like calibration, axes movements can be done by just using the rotary encoder on the Smart Controller. Print your 3D designs without PC, just with a g-code design stored on the SD card.