surely that's 85 degrees to each side,
and it can only go up to 90. Manufacturers specifications for these things are generally pretty meaningless anyway.
( Moon Girl Technologies horrendous beanbag, Mon 8 Jun 2009, 14:38, archived)

apprarently for this one
no, it's 85 degrees out of 180, not 90.
( the mighty badger Aphrodite, on a bar stool, by your side, Mon 8 Jun 2009, 14:59, archived)