This is a carrier board for the Pololu 1201 stepper controller module. This board holds the Pololu 1201 module and provides easy connections for Power, Stepper and Control wires. It has the same mounting holes as MBI stepper controllers and is a drop in replacement when set to half-step microstepping. The board enables you to select microstepping from full through 1/16 step (full, half, quarter, eighth, sixteenth). All components are through hole for easy assembly. Endstop connections are provided in both RJ-45 and CDROM style connectors so you can use opto or mechanical endstops, this will enable you to use mechanical endstops with current Gen3 electronics. Gen3 and Gen4 connections are supported on the board so you can use it with your current Gen3 motherboard and then move it to the Gen4 electronics with a simple change in cable. Connections for Ground, Enable, Step and Direction are broken out in a handy 4-pin header for easy connection to an Extruder Controller for stepper extruder operation.Kits are available at http://www.makergear.com/products/plastruder BOM and assembly instructions are available at http://www.johnyang.com/www/pscc15