A sphere, either an inflatable rubber ball (such as a basketball) or a solid polyurethane ball, is the fulcrum on which the board is balanced. By redistributing his/her weight across the board, the rider can move the board in any direction- side to side, forward and backward, twisting, diagonal, and full rotations or any combination of the movements. A rider can move the board vertically by doing an advanced maneuver called an Ollie. It can also be tilted in any direction and fully rotated. Sphere-and-ring boards provide the greatest freedom of movement of any type of balance board, allowing rotation about all axes and translation in both longitudinal and transverse direction. They, like wobble boards, simultaneously exercise muscles that are not exercised by use of boards that tilt in only two (opposite) directions.

When balancing or riding on a sphere-and-ring board the difficulty and ride speed, which is how fast the rider can move the board on the ball, is determined by the following:

1) Ring/rail size and shape

For safety, sphere-and-ring boards use a stop so that the board will remain on the ball. This stop is a ring or railing (or other shape of wall) on the underside of the board. The ball is placed inside the rail, so that if the board is moved too far in any direction during a ride, the ball hits the rail, prompting the rider to shift weight and lean in the opposite direction. The rail can be simply circular or oblong in shape or more complicated to use more of the potential play area, while keeping the rider within his/her safety zone.

Thus, the area within the rail is the play area for the board. If the rail is centered under the middle of the board the rider's weight is evenly distributed when standing equidistant from the rail. If the rail is offset (closer to the tail or nose of the board) the weight distribution is uneven. An uneven weight distribution feels more stability and contraction of one leg compared to the other.

2) Fulcrum/sphere size

Diameters of different models' balls range from 3 to 12 inches. A small fulcrum has less surface area contacting the board and ground producing less friction. A small ball will roll faster compared to a larger ball. A smaller ball keeps the board closer to the ground, which is usually advantageous for beginners to ground the board and stop quickly. A larger ball keeps the rider higher off the ground and usually lets the rider carve and tilt the board in greater angles.

3) Fulcrum/sphere weight

Weights of different models' balls range from 0.5 to 20.5 pounds. A light weight fulcrum requires less leg strength to move the board on the ball compared to a heavier ball. Respectively, when momentum is gained it takes more strength and coordination to control the board on a heavier ball.

4) Fulcrum/sphere rigidity

Fulcrum/sphere rigidity depends on the construction of the ball. A more rigid sphere (solid polyurethane ball) that resists deformation has a smaller fulcrum point compared to a sphere that deforms (inflatable ball). Again the smaller fulcrum point creates a faster ride requiring faster reflexive response. Thus rigid spheres provide more challenge compared to a ball that deforms when weight is applied.

5) Board construction and shape

Board construction. The board construction can either be flat or concave (the board is curved upward at the nose and tail). A board with concave moves with the natural motion of the hips (a ball and socket joint) likes a pendulum. A board that is flat requires the hips to slide in each direction.

Secondly, the shape of the board impacts the way the board rides. Current board shapes are eliptical, rounded rectangular, butterfly, skim/surf board shaped, or snowboard shaped. If the board is narrow at the nose compared to a square or rectangular nose, the narrow nose has less weight and is easier to move. This make carving turns faster and easier. If the tail of the board is wide and rectangular it is stable on the end.

Different models' size boards range from 18 to 58 inches in height.

In summary, a rigid small and light ball with a smaller board and railing size will ride faster requiring more reflexive coordination. A rigid large and heavy ball with a larger board and railing size will ride slower and will require greater leg strength to move the board.

Sphere-and-ring boards are increasingly being used by other board riders, as the freedom of movement makes them a more realistic trainer than other types of balance boards are (other than for skateboarding, which is mimicked more closely by a rocker-roller board with a tapered roller). They are also being seen as an activity in their own right, with tricks being adapted for them.

They have application in child development, gymnasiums, sport training and physiotherapy.

For safety, riding a sphere-and-ring board should not be attempted before becoming experienced riding a rocker-roller board leftward-rightward and backward-forward. Learning how to ride a sphere-and-ring board can be quite challenging. The key point is to initially keep your upper body stable while moving your lower body. While holding on to a stable surface, such as a counter top, move the board left and right, forward and backward, twist side to side, then move the board top clockwise and counterclockwise. This provides a neurological wake-up to your lower body while integrating your core stability of your upper body. Then try to stay centered and slowly let go of the stable surface. Let you body react to the movements of the board. Over time you will be able to actively move the board.

The original concept of a balance board using a sphere was patented in 1975 by Will Clarke England. Sphere-and-ring boards were not produced for marketing until 2005, when the Balance360 Board, developed by Kevin Curran and granted a patent in 2007 (the model whose underside is shown in the above photo) was released. It appears that that model's manufacturer is no longer doing business.

Current producers of sphere-and-ring boards include Si-Boards (10 board models, 5 solid polyurethane balls), Cool Boards (3 models, 2 adjustable inflatable balls) and Surf Ball (3 models, 1 adjustable inflatable ball).