From Team Associated:
The #81068 aluminum pillow balls are a direct replacement for the standard steel versions (#81067) supplied with the RC8B3 and RC8B3e kits.
Aluminum pillow balls reduce un-sprung mass in the front steering block assembly, resulting in a more aggressive steering feel. Perfect for smooth track conditions with high grip levels.
#81068 – MSRP: $29.99
Available January 2016