What physical feature is often used as a rule of thumb for determining appropriate prey size for a snake?

Answer

The prey item should be roughly the same diameter as the widest part of the snake’s body

A rule of thumb for appropriate prey size, especially for captive snakes, suggests that the prey item should approximate the diameter of the snake's widest body section.

What physical feature is often used as a rule of thumb for determining appropriate prey size for a snake?
dietreptilesnakeCarnivore