I know the name is long-winded, but it works. This is a hip hinge, not a Pigeon Stretch.
Skip to the :33 mark here for a video demonstration.
You'll notice a different sensation into the hip when properly hip hinging.
This can be useful for those who have attempted to stretch themselves into deeper Squats or Deadlifts without results.
Hold for over a minute and explore the "corners of hip."
It shouldn't be painful in the front of the hip.
Lower the box if it's not too challenging.