How to add a locking mechanism to a slider?

Hello,

please help in this technical issue.
a customer is looking for adding the functionality of a locking mechanism to his slider.

1) Does anybody know of a standard slider that has this feature integrated?

 2) Has somebody other ideas of integrating the locking feature?

Idea is to integrate locking between the 2 sliding part(black features). As you see one end is closed. so I need to lock the other end.

Hi Bart,

The Locking mechanism will be used when it is in close position. The sliding part is connected to a removable rack frame. I have already control the movement of the mechanism in up/down, cross car . As I mentioned one side of the slide is closed all I need is to find a locking mechanism. The locking mechanism should be strong enough to prevent the slide from rattling back and forth.

Below please find an screen shot of the sliding mechanism in the main system.