Hubs have a 4-bolt pattern on 4" circle. Hub assembly includes (4) L-44643 inner and outer bearings, (2) SL-122 double lipped grease seal, (2) SCP-100 cotter pin, (8) STN-506 lug nuts and pressed in bearing races. Pilot diameter 2.5 inches, flange diameter 5.56 inches.Also included is (2) chrome 1.980" bearing protectors (with bras) provide protection against damage from water and dirt entering the wheel bearings and make lubricating bearings a snap. Bearing protectors prevent wheel bearing failure on boat, snowmobile, ATV, horse, RV and utility trailers. Proven in use for over 35 years and billions of miles of service! PLEASE NOTE: This kit will only fit trailer spindles that have a 1" bearing surface with a 1.25" seal surface. If you have any questions before ordering - call or email us, we can assist if you have a different spindle/seal size.