The shoulder pull-down is an absolutely fantastic way of duplicating the partner shoulder push down (or depress) exercise. In fact, it allows some bells and whistles which the ordinary (but lovely!) shoulder push down exercise cannot achieve. And, especially good in this era, is that this is a solo movement. All you need is a chair whose base you can grasp with one hand while you are sitting. It can be as gentle as you need, all the way though to as strong as you want. Go slowly and carefully in the beginning.
All the side neck muscles are stretched, but minor changes of positions can make this into a levator scapulae stretch, too. And even more importantly for people who work on computers (and isn't that everyone these days?), once the shoulder is drawn down, and the head taken sideways (or forwards and sideways), then all the *brachial plexus* is taken though their full movements, so this exercise can help with hand, wrist, and elbow problems, in time.
The T-shirts Kit talks about, made by Jim MacAirt:
Find the audio file of this video at https://supplementary-material.s3.us-west-2.amazonaws.com/Shoulder+pull-down+_+Stretch+Therapy.mp3.