Boat trailer roller brackets are for wobble rollers and keel rollers and bunks. Haway make different sizes and models of wobble roller brackets and keel roller brackets. These roller brackets are all made of high quality steel and hot dip galvanized surface finish. Typically they need bolts or U bolts to mount on trailers. Galvanized bolts and U bolts can be supplied together. If you do not want to buy roller and bracket separately we can assemble them within our factory and send complete boat trailer roller kit to you.