VRC Inventor Parts.........HELP!! :P
 

I need a VEX part, it is the Slider pieces which allow linear motion. If it is unclear about what i am referring to as slider u can have a look at it here

http://www.vexrobotics.com/catalog/product/gallery/image/11756/id/891/

the two pieces that allow us linear motion.
I am not able to find them in VEX Cad library so if any one can help me..in any possible way.........PLEASE!

THANK YOU :D