A clevis self-locking hook Grade 80 is a type of hook used in rigging and lifting applications. It is designed to securely attach to various types of lifting equipment, such as chains or slings, to connect them to loads or anchor points. 
The "self-locking" feature of this type of hook is a safety mechanism that helps prevent accidental disengagement. It involves a locking mechanism that automatically closes and locks the hook once it is engaged with a load or anchor point. This helps ensure that the hook remains securely attached and reduces the risk of the load becoming detached during lifting or hoisting operations.
Clevis self-locking hooks Grade 80 are commonly used in industries like construction, manufacturing, and material handling where heavy loads need to be lifted and secured safely.