This is a mounting bracket for the Wanhao Duplicator i3 or Maker Select to allow replacement of the original melzi board with a RAMPS, with either the Mega2560 8 bit processor or with the Re-ARM 32-bit processor.
There is also accomodation for two kinds of bed mosfets, and a version with an additional accommodation for a small "MOS Module" irf520 board which can be used to drive a white LED strip from one of the servo headers on the RAMPS.
You may notice that one of the Mega2560 mounting holes is a little bit off - that's because on the Re-ARM, at least on my BIQU Re-ARM clone, that hole has moved slightly. I found a medium position where you should be able to use that hole with either one.
An effort has been made to prevent crowding the reset buttons on unofficial RAMPS versions that stick out the side.
All board mounting holes are 2.7mm ID and should self-tap with M3 screws. If you find that they break off when printed in PLA, please increase your extrusion temperature slightly and try again.