Passive forearm pronation (Forearm supinators stretch, sitting)

Sit upright in a chair.
Bend your elbow and tuck it in to your side keeping your wrist and fingers relaxed.
Hold your forearm with your opposite hand, just below wrist level.
Use your opposite hand to turn your forearm so that your palm turns towards the floor.
Hold this position in a stretch before relaxing the arm.
Ensure you do not lean your body with this movement.