I really think this ball is a 55cm as it seems really small compared to other 65cm balls I have used. Also the legs are a great idea but they just fold outwards when I sit on the ball. Overall, I wish I would have went with an inexpensive ball instead of paying more for a ball with legs.When I sit on it I do feel relief in my lower back/hips so it will do. However, my knees point up so I am not sure how long it will be comfortable. If I stretch out my legs it helps but the ball wants to roll.
Rating: [3 of 5 Stars!]