Kit Includes: (2) Front Racing Wheel Hub with Bearings and Bolts (2) Rear Racing Wheel Hub (1" bore) with Bolts Front Hub Specs: Brand: BMI Karts Material: Aluminum Lightweight Hub Style: Front / Floater American Bolt Patterns: (3) 1/4-28 Bolt Holes on a 2-1/2" Bolt Circle (3) 5/16-24 Bolt Holes on a 2-1/2" Bolt Circle Bolt to Bolt Measurement: 2.16" (55mm) Bearing OD Size: 1-3/8" Bearing ID / Spindle Shaft Size: 5/8" Rear Hub Specs: Brand: BMI Karts Material: Aluminum Lightweight Hub Style: Rear Axle Size / Bore: 1" Keyway: 1/4" Bolt Patterns: (3) 1/4-28 Bolt Holes on a 2-1/2" Bolt Circle (3) 5/16-24 Bolt Holes on a 2-1/2" Bolt Circle Bolt to Bolt Measurement: 2.16" (55mm)