This Timing Pulley has 10 teeth. it is made of Aluminium with a set screw for attachment. Bore diameter is 5mm. It has 2 flanges (dia 20mm) suiting a belt width up to 6mm. Overall length is 17mm.

This stepper motor is the standard for RepRaps and many of their derivatives.
Now includes a flat on the shaft for better grip of pulleys

The DM420A is a type of two-phase hybrid stepping motor driver for one motor. It is designed for use with 2-phase hybrid stepper motor of all kinds with 20mm to 36mm outside diameter and less than 2.0A per phase current.
Input Voltage: 12VDC to 36VDC.
Input Power: <2A up to 40W
Output Current: 0.44A - 2.83A(peak)
Inputs and Outputs are opto-isolated.
Overvoltage, under voltage, overcorrect, phase short circuit protection
Operating Temperature: -10 to 45 degreesC
15 channel subdivision and automatic idle-current reduction. 8 channels output phase current setting
Replaces the older MD542 Driver

This stepper motor is the standard for smaller 3d printers such as the RepRap Wallace and Printrbot machines