What should be ensured about the self belay key during use?

The crucial aspect of the self belay key during use is that it must remain securely attached. This ensures the safety of the user by preventing any accidental disengagement that could lead to a fall or other safety hazard. The self belay system is designed to provide a lifeline by connecting the user to a safety anchor, and if the key is not securely attached, the entire safety system can fail. Maintaining a secure attachment is vital for ensuring that the self belay system functions as intended, providing the necessary protection during activities that involve vertical movement or heights.