This pose is known as One Legged King Pigeon.
It helps to open pretty much every part of your body- chest, hips, shoulders, back. For this reason it can be difficult to get into if you lack flextbitiy in any of these areas. That’s where the strap comes in! On the flip side, if this pose is easy for you, you can use the strap to deepen the pose and make it more challenging.

Ajna Organic Jute Yoga Mat and Strap available here-
www.ajnawellbeing.com

And on Amazon here-
https://www.amazon.com/ajna

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