X-axis idler for linear stepping motor.

I designed the x-axis idler for linear stepping motor as a part of my compact size Reprap.
The idler uses two of 608 ball bearing and two of LM8UU holder as following link.
http://www.thingiverse.com/thing:86191
This idler is pair of the X-axis linear motor holder as following link.
http://www.thingiverse.com/thing:95547