About this item Set of one 12″ x 2″ electric and hydraulic brake (left side), fit most 5200lbs 6000lbs 7000lbs axle Center hole diameter: 3-1/4″ Fits the wheel bolt pattern 6 lug or 8 lug,fits spline size #42 steel drum.Bolt hole spacing: 2.0″ O.C. around the top,Bolt hole spacing: 3.0″ O.C.across the bottom Replace dexter brakes K23-180-00 K23-181-00 replace Axletech B12E-22 (12×2) Al-Ko Lippert,etc The trailer brakes are NOT self adjusting, unlike most drum brakes on cars and trucks,need to be done when installed and periodically thereafter.If you cannot adjust yourself, please find a professional adjustment JADODE electric and hydraulic trailer brake parts Making it an Ideal Choice for Travelers Seeking a Hassle-Free Power Solution.Note make sure it matches you size,hub has to fit over