Flow Valves

[s5511]

We have to pistons, one on each side of our robot, that lifts our climber and intake mechanism up. When it retracts and goes down back into the robot, the pistons retract at a very high velocity and the mechanism 'smashes' into the robot. We still want the pistons to push the mechanism up very quickly, but we don't want them to retract as fast. I heard that a flow valve could fix this problem.

Which flow valve would I need to make the piston retract slower than it rises?

This one: http://www.andymark.com/product-p/am-2897.htm
or this one: http://www.andymark.com/product-p/am-2690.htm

Also, how many of these flow valves would I need per piston?

Thanks!!