SPEED-SPEC 40mm Axle Bearing, 40mm ID x 80mm OD, Sold Individually

Full #52100 Chrome Steel .. Hi-Temp / Hi-Viscosity Race Quality Lubricant
‘Speed Specs’ : Rubber Seals .. C3 Clearance .. P5 Clearance

So these are aimed at folks who want a ‘better steel bearing, something a little less expensive than say a ‘best’ / ceramic hybrid bearing but something built to the very high standards and tight tolerances normally only found in bearings double the price. As such, their name: “Speed Spec” built to specs designed for speed. These sport rubber seals so folks can clean / re-lube . . . make last longer / run smoother.