This is Version 2 of the Gripper kit. It is a little lighter since some parts are now hollow. This is less forgiving on the servos. I recommend to print the piston rods in metal so they don't break, but you can still get them in plastic if you want to save a few bucks.
You will also need this: http://shpws.me/MwbB
and these: http://shpws.me/Ly5P
For instructions on how to make it work please follow thiss thread from Jamie McShan:Â http://astromech.net/forums/showthread.php?27377-TexMex-Gripper-Arm-that-actually-works