Spud, Inc.Deluxe Machine Cable Attachment Handles (Single D Handles)

What is the diameter of the handles. And are these designed for pushing or pulling?

Do these spin/rotate or are they a solid grip?

Could I use these for strict body weight pull ups?

What's the purpose of the nylon loop above the ring - attach the carabiner directly to the ring for a shorter handle but to the loop for a longer one?