Rx STEEL | MGP 710 GREEN bearings have 7 steel balls.

Features:

• Inner and outer races plus the steel balls are highly polished to a mirror like finish
  
  
• Raceway is optimized for the ball and raceway contact area and contact angle.
  
  
• Removable non-contact rubber shields for easy cleaning and zero friction.
  
  
• 1 Year Limited Warranty 
  
  
• Steel balls are 52100 carbon, chromium steel (HRC 67)
  
  
• Inner and Outer raceways are 52100 carbon, chromium steel (HRC 67)
  
  
• Retainer is 6/6 Nylon special additive making it more resistant to breakage
  
  
• Pre-lubricated with Rx Lube Drops®, a low viscosity oil to reduce friction
  
  
• ABEC-7 rating, Ball deviation grade 10, Noise is under 31db.