Check out the whole article including visuals and a free workout here:

https://courses.coachbachmann.com/deep-side-bends-one-arm-handstands/

A Deep Side Bend is an advanced handstand drill. It is essential on the way to the one arm handstand, it will open doors towards more advanced handstand drills and add a huge amount of freedom of movement to your handstand practice.

Deep Side bends require only some strength, lots of very specific coordination and mobility in your back, sides and even hips.