Is the cam auto lock to stop rope slip out?

There is a locking function on the SAKA FOLDABLE knee ascender. 

In the image the white bungee cord is wrapped around the locking component. You need to flip this down when you open the cam to install the rope. Once the rope in installed and the cam is up against the rope the cam won't go far enough back to allow the rope to slip out. Let us know if you have any other questions.