The patented Twinstop®-System does provide two independent working blocking mechanisms:

Speed controlled blocking mechanism:

In the event of a fall the accelerating speed is activating the locking mechanism and blocks the fall arrester in the rail.
Pros:

• Guaranteed function in negative inclined ladders certified up to an angle of -20°
• Guaranteed function at the event of a fall back
• Guaranteed function at spring fracture
• Guaranteed function at changed geometry between the full body harness, the fall arrester and the climber. As well as at different material (elastic webbing) design (chest attachment, belly attachment), and from size and weight of the climber

Vector controlled blocking mechanism:

Ensures the advanced features of common systems, for instance to block the arrester manually in the rail in case of leaning in the harness while resting from climbing.