M8 = 8mm Bore x M8 Thread. M12 = 12mm Bore x M12 Thread. M10 = 10mm Bore x M10 Thread. M6 = 6mm Bore x M6 Thread. M5 = 5mm Bore x M5 thread.
This product would be best suited for individuals who require quality bearings or joint components for their bike trike, karting, or go-kart tracks.
