Stated size is incorrect.
I bought this for my office chair to improve sitting for long periods of time.  First, it is only 17&#34; x 15&#34; not 18 x 16.  It does not fit for me in that it is too narrow for my body.  My legs hurt from the overhang while using.  It might be great for a smaller person but not for me.  I am 6 foot and weigh 250 pounds.
Rating: 2 stars