• plastic exercise ball chair without arms
• metal balance ball chair without arms
• metal exercise ball chair with arms
• therapy ball on top of holder, "ball bowl", or stabilizer ring
• exercise ball chair with legs
• textured balance ball chairs
• exercise ball chair with weighted bottom
• The Ergo Chair™; "oval" shaped ball that sits in a "1/2 moon" frame
  

Which TYPE of ball chair you choose will depend on three main factors:
1. How much money you want to spend (anywhere from $40-$450).
2. What size and type of exercise ball chair you want/need for the proper seating position.
3. What "issues" the ball chair will be addressing (i.e., dynamic seating, posture, balance, comfort, sensory issues, etc.).

My suggestion?

If it is for an adult or older child, the Ergo Chair ™ will do. Oh, how comfortable you will be!

If it is for a younger child, then any of the exercise balls with a weighted bottom, with legs, or that sits in a stabilizing ring/holder will do.

If it is for sensory issues only (i.e., dynamic seating, proprioceptive, or vestibular input), the Ergo Chair™, the Sit-or-Go (tm) Sit Ball cover and ball would be a great choice. Even if this one isn't available or affordable know that the continuous postural adjustments a child will need to make while sitting on such a comfortable "seat" may mean the difference between being able to pay attention or not in the classroom, between A's and C's. The more they have to adjust, the more input they receive, the more calm and focused they will be!
Just remember to get the right size ball for a proper fit (usually knees and hips bent at 90 degrees, no more). Hint: If you get the metal exercise ball chairs, such as the Ergo Chair, they are height adjustable!

Ball chairs: Truly an inventive, ergonomic, dynamic, outrageously comfortable, seating alternative!