Upgrade to K2 ILQ-9 Pro bearings for better performance. 

What's the difference between these and the K2 ILQ-9 Classic Plus bearings? Whilst both use 6 ball bearings and a self-lubricating nylon retainer for less friction, the ILQ-9 Pro bearings features SCRS (S-Channel Rubber Shields) for less contamination.  This makes them faster and more manageable for excess dirt and grease. Perfect for racing.