There’s a ball on the seat for massage that comes through the seating.    The heat and massage stop working a month after chairs arrived.  Which was a big reason I bought them for the heat on my spine.    You can’t adjust the seating to your liking.    The does rise all the way up … slowly which means you be patient or kinda climb over .  The chair does not go comply back which I’m ok with.  
It’s sad about the heat and massage it really should have lasted for longer than a month.    I bought two and they are the same.   Putting them together I had to get help.  You have to line them up just right but it not hard just awkward