What type of criteria do the type of hitch and the number of shackles fall under?

The type of hitch and the number of shackles are closely related to the sizing of slings used in rigging applications. When selecting a sling for a particular lift, it's essential to consider the type of hitch because different hitches can affect the sling's capacity and how the load is distributed. Additionally, the number of shackles plays a role in load management and stability, influencing the overall effectiveness of the rigging system.

Sizing of slings involves various considerations such as the load weight, lifting angle, and type of hitch selected. Ensuring that the slings are properly sized according to these criteria helps maintain safety and efficiency during lifting operations. This is why the correct classification for the criteria involving the type of hitch and the number of shackles is indeed under sizing of slings. Other options, while relevant to lifting, do not directly address the specific interplay between hitch types and shackle counts in relation to sling sizing.