This is a Genuine Dexter Hub Kit K08-248-90
This is everything you need, except the axle nut or washer, cotter pin, (they dont wear out, and can be re-used)
This hub fits a standard 3500 pound axle, either spring type, or "torflex". Bolt pattern is 5 bolt on a 4-1/2" inch bolt circle used on many trailers. Studs are standard 1/2"-20 thread.
This is what a 5 on 4 1/2 bolt pattern measures.