The GP-S Bearing from Independent Trucks are high-quality skateboard bearings with an excellent price/quality relationship.
These bearings were developed specifically for skateboarding. They come with polished inner running surfaces which are abrasion-resistant and designed for high speeds. They also feature a protective, water-resistant Shell Light lubricant.
The outer side of the bearing is equipped with a sturdy metal shield to prevent dirt from entering them. The inside doesn't have a shield so it can be easily cleaned - smart! That also increases the bearing's overall durability while locking into high speeds. The "super cage" design helps with the durability, too.