Traditional spherical bearing - sized to fit standard skateboard truck kingpin dimensions - a perfect choice for DIY (do it yourself) truck mods.  Each bearing is made from chromoly steel with heat-treated protective coating for corrosion resistance. These bearings feature a PTFE race liner and are self-lubricating.  Bore size is 0.3750 inch.  Use standard cleaner and lube for periodic maintenance.  Sold individually.