Made in Japan! New KSK brand 1614 RS set of bearings. Set of 4. Much smoother/better quality than the cheap factory installed ones. Major upgrade. Very easy to install. Outer diameter is 1.125 or 1-1/8". Inner diameter is .375 or 3/8". Thickness is .375. These fit newer Skyway Tuff 2's that came with sealed bearings. Please see photo for reference. Thanks for looking!!