Smoke free home.
2 NadaChairs (one black, one navy) price is per item.
Provides back support when you have to sit somewhere without back support (example: bleachers, canoe, piano bench) or when you need a little extra prompting to maintain good posture (i.e. computer desk).
The carry-handles velcro onto the unit but when detached can be used to keep the nadachair strapped around your waist (great if you want to jump up and cheer without having to hold onto the NadaChair).

I found this quick demo on youtube:
https://www.youtube.com/wat...
And this review from a physical therapist:
https://www.youtube.com/wat...

The black NadaChair has the "CushShins" accessory (https://www.nadachair.com/p...) to create a larger support area and disperse the leaning weight of the body over about three times the area of the shin.
The navy NadaChair has the "StretchStraps" accessory (https://www.nadachair.com/p...) allowing sit on a flat surface with legs out stretched by extending the loops sufficiently to engage the feet and the original instruction manual (which includes some hints for how to also use this for stretching).