This Galvanized Boat Trailer Axle will fit the industry standard 5 Lug 3,500lb Trailer hubs, which are not included with the axle. The Bearing Size which fits this axles spindles are 68149 (1 3/8") and 44649 (1/16"). The Grease Seal Surface area will fit a 1.72" ID Grease seal. This Axle features a Hot-Dipped Galvanized Coating as well a sturdy 2"x2" Straight beam, which makes it perfect for use on Boat Trailers in Saltwater or freshwater environments.