Typically, a round or oval shaped hand-held device to aid steering control. It attaches to the steering wheel by use of a small bracket or clamp. 

Sometimes it is also known as a steering ball, steering mushroom, or steering aid. There are many different types of steering aids, each designed to help drivers with upper limb and hand function issues.

Enables one-handed operation of a steering wheel with either the left or the right upper limb. Whilst some people may prefer to steer one-handed by using the palm of their hand on the standard steering wheel, a steering aid will facilitate a less effortful and more secure grip on the steering wheel.

Can be used in combination with other adaptations when required, such as hand control adaptations, left foot accelerator or modified secondary controls such as anindicator stalk extension ora wireless secondary control system

• Is there sufficient range of movement and strength in the upper limb  for the steering task? If there is weakness with the wrist or with grip or other hand function issues, there are more specialist steering aids,for example, glove and peg devices. Advice on the suitability of the more specialist steering aids is recommended. 
• A vehicle with variable power assisted steering could be helpful, alternatively lightened power assisted steering may be required.
• Placement of the bracket is down to driver preference. The upper half of the steering wheel is generally favoured because it is easier to initiate turns from the upper half of the steering wheel than from the lower half. However, placing the aid at the 12 o’clock position should be avoided as this can impact on control over the steering, obscure vision of dashboard information (speedo, warning lights etc.,) and increase the risk of head and/or face injury in the event of a collision.
• Suitable for vehicles with and without airbags. 

A quick release version allows simple and fast removal of the steering spinner, should other drivers not require it for driving.  This will leave behind a small bracket on the steering wheel but this shouldn’t impact on ability to steer conventionally.